acons
 -- Scheme Procedure: acons key value alist
     Add a new key-value pair to ALIST.  A new pair is created whose car is KEY and whose cdr is VALUE, and the pair is consed onto ALIST, and the new list is returned.  This function is not destructive; ALIST is not modified.

sloppy-assq
 -- Scheme Procedure: sloppy-assq key alist
     Behaves like assq but does not do any error checking. Recommended only for use in Guile internals.

sloppy-assv
 -- Scheme Procedure: sloppy-assv key alist
     Behaves like assv but does not do any error checking. Recommended only for use in Guile internals.

sloppy-assoc
 -- Scheme Procedure: sloppy-assoc key alist
     Behaves like assoc but does not do any error checking. Recommended only for use in Guile internals.

assq
 -- Scheme Procedure: assq key alist
 -- Scheme Procedure: assv key alist
 -- Scheme Procedure: assoc key alist
     Fetch the entry in ALIST that is associated with KEY.  To decide whether the argument KEY matches a particular entry in ALIST, assq compares keys with eq?, assv uses eqv? and assoc uses equal?.  If KEY cannot be found in ALIST (according to whichever equality predicate is in use), then return #f.  These functions return the entire alist entry found (i.e. both the key and the value).

assv
 -- Scheme Procedure: assv key alist
     Behaves like assq but uses eqv? for key comparison.

assoc
 -- Scheme Procedure: assoc key alist
     Behaves like assq but uses equal? for key comparison.

assq-ref
 -- Scheme Procedure: assq-ref alist key
 -- Scheme Procedure: assv-ref alist key
 -- Scheme Procedure: assoc-ref alist key
     Like assq, assv and assoc, except that only the value associated with KEY in ALIST is returned.  These functions are equivalent to

          (let ((ent (ASSOCIATOR KEY ALIST)))
            (and ent (cdr ent)))

     where ASSOCIATOR is one of assq, assv or assoc.

assv-ref
 -- Scheme Procedure: assv-ref alist key
     Behaves like assq-ref but uses eqv? for key comparison.

assoc-ref
 -- Scheme Procedure: assoc-ref alist key
     Behaves like assq-ref but uses equal? for key comparison.

assq-set!
 -- Scheme Procedure: assq-set! alist key val
 -- Scheme Procedure: assv-set! alist key value
 -- Scheme Procedure: assoc-set! alist key value
     Reassociate KEY in ALIST with VALUE: find any existing ALIST entry for KEY and associate it with the new VALUE.  If ALIST does not contain an entry for KEY, add a new one.  Return the (possibly new) alist.

     These functions do not attempt to verify the structure of ALIST, and so may cause unusual results if passed an object that is not an association list.

assv-set!
 -- Scheme Procedure: assv-set! alist key val
     Behaves like assq-set! but uses eqv? for key comparison.

assoc-set!
 -- Scheme Procedure: assoc-set! alist key val
     Behaves like assq-set! but uses equal? for key comparison.

assq-remove!
 -- Scheme Procedure: assq-remove! alist key
 -- Scheme Procedure: assv-remove! alist key
 -- Scheme Procedure: assoc-remove! alist key
     Delete the first entry in ALIST associated with KEY, and return the resulting alist.

assv-remove!
 -- Scheme Procedure: assv-remove! alist key
     Behaves like assq-remove! but uses eqv? for key comparison.

assoc-remove!
 -- Scheme Procedure: assoc-remove! alist key
     Behaves like assq-remove! but uses equal? for key comparison.

make-arbiter
 -- Scheme Procedure: make-arbiter name
     Return an object of type arbiter and name NAME. Its state is initially unlocked.  Arbiters are a way to achieve process synchronization.

try-arbiter
 -- Scheme Procedure: try-arbiter arb
     Return #t and lock the arbiter ARB if the arbiter was unlocked. Otherwise, return #f.

release-arbiter
 -- Scheme Procedure: release-arbiter arb
     Return #t and unlock the arbiter ARB if the arbiter was locked. Otherwise, return #f.

async
 -- Scheme Procedure: async thunk
     Create a new async for the procedure THUNK.

system-async
 -- Scheme Procedure: system-async thunk
     Create a new async for the procedure THUNK.  Also add it to the system's list of active async objects.

async-mark
 -- Scheme Procedure: async-mark a
     Mark the async A for future execution.

system-async-mark
 -- Scheme Procedure: system-async-mark a
     Mark the async A for future execution.

run-asyncs
 -- Scheme Procedure: run-asyncs list_of_a
     Execute all thunks from the asyncs of the list LIST_OF_A.

noop
 -- Scheme Procedure: noop . args
     Do nothing.  When called without arguments, return #f, otherwise return the first argument.

unmask-signals
 -- Scheme Procedure: unmask-signals
     Unmask signals. The returned value is not specified.

mask-signals
 -- Scheme Procedure: mask-signals
     Mask signals. The returned value is not specified.

display-error
 -- Scheme Procedure: display-error stack port subr message args rest
     Display an error message to the output port PORT. STACK is the saved stack for the error, SUBR is the name of the procedure in which the error occurred and MESSAGE is the actual error message, which may contain formatting instructions. These will format the arguments in the list ARGS accordingly.  REST is currently ignored.

display-application
 -- Scheme Procedure: display-application frame [port [indent]]
     Display a procedure application FRAME to the output port PORT. INDENT specifies the indentation of the output.

display-backtrace
 -- Scheme Procedure: display-backtrace stack port [first [depth]]
     Display a backtrace to the output port PORT. STACK is the stack to take the backtrace from, FIRST specifies where in the stack to start and DEPTH how much frames to display. Both FIRST and DEPTH can be #f, which means that default values will be used.

backtrace
 -- Scheme Procedure: backtrace
     Display a backtrace of the stack saved by the last error to the current output port.

not
 -- Scheme Procedure: not x
     Return #t iff X is #f, else return #f.

boolean?
 -- Scheme Procedure: boolean? obj
     Return #t iff OBJ is either #t or #f.

char?
 -- Scheme Procedure: char? x
     Return #t iff X is a character, else #f.

char=?
 -- Scheme Procedure: char=? x y
     Return #t iff X is the same character as Y, else #f.

char<?
 -- Scheme Procedure: char<? x y
     Return #t iff X is less than Y in the ASCII sequence, else #f.

char<=?
 -- Scheme Procedure: char<=? x y
     Return #t iff X is less than or equal to Y in the ASCII sequence, else #f.

char>?
 -- Scheme Procedure: char>? x y
     Return #t iff X is greater than Y in the ASCII sequence, else #f.

char>=?
 -- Scheme Procedure: char>=? x y
     Return #t iff X is greater than or equal to Y in the ASCII sequence, else #f.

char-ci=?
 -- Scheme Procedure: char-ci=? x y
     Return #t iff X is the same character as Y ignoring case, else #f.

char-ci<?
 -- Scheme Procedure: char-ci<? x y
     Return #t iff X is less than Y in the ASCII sequence ignoring case, else #f.

char-ci<=?
 -- Scheme Procedure: char-ci<=? x y
     Return #t iff X is less than or equal to Y in the ASCII sequence ignoring case, else #f.

char-ci>?
 -- Scheme Procedure: char-ci>? x y
     Return #t iff X is greater than Y in the ASCII sequence ignoring case, else #f.

char-ci>=?
 -- Scheme Procedure: char-ci>=? x y
     Return #t iff X is greater than or equal to Y in the ASCII sequence ignoring case, else #f.

char-alphabetic?
 -- Scheme Procedure: char-alphabetic? chr
     Return #t iff CHR is alphabetic, else #f. Alphabetic means the same thing as the isalpha C library function.

char-numeric?
 -- Scheme Procedure: char-numeric? chr
     Return #t iff CHR is numeric, else #f. Numeric means the same thing as the isdigit C library function.

char-whitespace?
 -- Scheme Procedure: char-whitespace? chr
     Return #t iff CHR is whitespace, else #f. Whitespace means the same thing as the isspace C library function.

char-upper-case?
 -- Scheme Procedure: char-upper-case? chr
     Return #t iff CHR is uppercase, else #f. Uppercase means the same thing as the isupper C library function.

char-lower-case?
 -- Scheme Procedure: char-lower-case? chr
     Return #t iff CHR is lowercase, else #f. Lowercase means the same thing as the islower C library function.

char-is-both?
 -- Scheme Procedure: char-is-both? chr
     Return #t iff CHR is either uppercase or lowercase, else #f. Uppercase and lowercase are as defined by the isupper and islower C library functions.

char->integer
 -- Scheme Procedure: char->integer chr
     Return the number corresponding to ordinal position of CHR in the ASCII sequence.

integer->char
 -- Scheme Procedure: integer->char n
     Return the character at position N in the ASCII sequence.

char-upcase
 -- Scheme Procedure: char-upcase chr
     Return the uppercase character version of CHR.

char-downcase
 -- Scheme Procedure: char-downcase chr
     Return the lowercase character version of CHR.

debug-options-interface
 -- Scheme Procedure: debug-options-interface [setting]
     Option interface for the debug options. Instead of using this procedure directly, use the procedures debug-enable, debug-disable, debug-set! and debug-options.

with-traps
 -- Scheme Procedure: with-traps thunk
     Call THUNK with traps enabled.

memoized?
 -- Scheme Procedure: memoized? obj
     Return #t if OBJ is memoized.

unmemoize
 -- Scheme Procedure: unmemoize m
     Unmemoize the memoized expression M,

memoized-environment
 -- Scheme Procedure: memoized-environment m
     Return the environment of the memoized expression M.

procedure-name
 -- Scheme Procedure: procedure-name proc
     Return the name of the procedure PROC

procedure-source
 -- Scheme Procedure: procedure-source proc
     Return the source of the procedure PROC.

procedure-environment
 -- Scheme Procedure: procedure-environment proc
     Return the environment of the procedure PROC.

local-eval
 -- Scheme Procedure: local-eval exp [env]
     Evaluate EXP in its environment.  If ENV is supplied, it is the environment in which to evaluate EXP.  Otherwise, EXP must be a memoized code object (in which case, its environment is implicit).

debug-object?
 -- Scheme Procedure: debug-object? obj
     Return #t if OBJ is a debug object.

c-registered-modules
 -- Scheme Procedure: c-registered-modules
     Return a list of the object code modules that have been imported into the current Guile process.  Each element of the list is a pair whose car is the name of the module, and whose cdr is the function handle for that module's initializer function.  The name is the string that has been passed to scm_register_module_xxx.

c-clear-registered-modules
 -- Scheme Procedure: c-clear-registered-modules
     Destroy the list of modules registered with the current Guile process. The return value is unspecified.  Warning: this function does not actually unlink or deallocate these modules, but only destroys the records of which modules have been loaded.  It should therefore be used only by module bookkeeping operations.

dynamic-link
 -- Scheme Procedure: dynamic-link filename
     Open the dynamic library called FILENAME.  A library handle representing the opened library is returned; this handle should be used as the DOBJ argument to the following functions.

dynamic-object?
 -- Scheme Procedure: dynamic-object? obj
     Return #t if OBJ is a dynamic library handle, or #f otherwise.

dynamic-unlink
 -- Scheme Procedure: dynamic-unlink dobj
     Unlink the indicated object file from the application.  The argument DOBJ must have been obtained by a call to dynamic-link.  After dynamic-unlink has been called on DOBJ, its content is no longer accessible.

dynamic-func
 -- Scheme Procedure: dynamic-func name dobj
     Search the dynamic object DOBJ for the C function indicated by the string NAME and return some Scheme handle that can later be used with dynamic-call to actually call the function.

     Regardless whether your C compiler prepends an underscore _ to the global names in a program, you should not include this underscore in FUNCTION.  Guile knows whether the underscore is needed or not and will add it when necessary.

dynamic-call
 -- Scheme Procedure: dynamic-call func dobj
     Call the C function indicated by FUNC and DOBJ. The function is passed no arguments and its return value is ignored.  When FUNCTION is something returned by dynamic-func, call that function and ignore DOBJ. When FUNC is a string , look it up in DYNOBJ; this is equivalent to

          (dynamic-call (dynamic-func FUNC DOBJ #f))

     Interrupts are deferred while the C function is executing (with SCM_DEFER_INTS/SCM_ALLOW_INTS).

dynamic-args-call
 -- Scheme Procedure: dynamic-args-call func dobj args
     Call the C function indicated by FUNC and DOBJ, just like dynamic-call, but pass it some arguments and return its return value.  The C function is expected to take two arguments and return an int, just like main:

          int c_func (int argc, char **argv);

     The parameter ARGS must be a list of strings and is converted into an array of char *.  The array is passed in ARGV and its size in ARGC.  The return value is converted to a Scheme number and returned from the call to dynamic-args-call.

dynamic-wind
 -- Scheme Procedure: dynamic-wind in_guard thunk out_guard
     All three arguments must be 0-argument procedures. IN_GUARD is called, then THUNK, then OUT_GUARD.

     If, any time during the execution of THUNK, the continuation of the dynamic_wind expression is escaped non-locally, OUT_GUARD is called.  If the continuation of the dynamic-wind is re-entered, IN_GUARD is called.  Thus IN_GUARD and OUT_GUARD may be called any number of times.

          (define x 'normal-binding)
          => x
          (define a-cont  (call-with-current-continuation
          		  (lambda (escape)
          		     (let ((old-x x))
          		       (dynamic-wind
          			  ;; in-guard:
          			  ;;
          			  (lambda () (set! x 'special-binding))

          			  ;; thunk
          			  ;;
          		 	  (lambda () (display x) (newline)
          				     (call-with-current-continuation escape)
          				     (display x) (newline)
          				     x)

          			  ;; out-guard:
          			  ;;
          			  (lambda () (set! x old-x)))))))

          ;; Prints:
          special-binding
          ;; Evaluates to:
          => a-cont
          x
          => normal-binding
          (a-cont #f)
          ;; Prints:
          special-binding
          ;; Evaluates to:
          => a-cont  ;; the value of the (define a-cont...)
          x
          => normal-binding
          a-cont
          => special-binding

environment?
 -- Scheme Procedure: environment? obj
     Return #t if OBJ is an environment, or #f otherwise.

environment-bound?
 -- Scheme Procedure: environment-bound? env sym
     Return #t if SYM is bound in ENV, or #f otherwise.

environment-ref
 -- Scheme Procedure: environment-ref env sym
     Return the value of the location bound to SYM in ENV. If SYM is unbound in ENV, signal an environment:unbound error.

environment-fold
 -- Scheme Procedure: environment-fold env proc init
     Iterate over all the bindings in ENV, accumulating some value. For each binding in ENV, apply PROC to the symbol bound, its value, and the result from the previous application of PROC. Use INIT as PROC's third argument the first time PROC is applied. If ENV contains no bindings, this function simply returns INIT. If ENV binds the symbol sym1 to the value val1, sym2 to val2, and so on, then this procedure computes:

            (proc sym1 val1
                  (proc sym2 val2
                        ...
                        (proc symn valn
                              init)))

     Each binding in ENV will be processed exactly once. environment-fold makes no guarantees about the order in which the bindings are processed. Here is a function which, given an environment, constructs an association list representing that environment's bindings, using environment-fold:

            (define (environment->alist env)
              (environment-fold env
                                (lambda (sym val tail)
                                  (cons (cons sym val) tail))
                                '()))

environment-define
 -- Scheme Procedure: environment-define env sym val
     Bind SYM to a new location containing VAL in ENV. If SYM is already bound to another location in ENV and the binding is mutable, that binding is replaced.  The new binding and location are both mutable. The return value is unspecified. If SYM is already bound in ENV, and the binding is immutable, signal an environment:immutable-binding error.

environment-undefine
 -- Scheme Procedure: environment-undefine env sym
     Remove any binding for SYM from ENV. If SYM is unbound in ENV, do nothing.  The return value is unspecified. If SYM is already bound in ENV, and the binding is immutable, signal an environment:immutable-binding error.

environment-set!
 -- Scheme Procedure: environment-set! env sym val
     If ENV binds SYM to some location, change that location's value to VAL.  The return value is unspecified. If SYM is not bound in ENV, signal an environment:unbound error.  If ENV binds SYM to an immutable location, signal an environment:immutable-location error.

environment-cell
 -- Scheme Procedure: environment-cell env sym for_write
     Return the value cell which ENV binds to SYM, or #f if the binding does not live in a value cell. The argument FOR-WRITE indicates whether the caller intends to modify the variable's value by mutating the value cell.  If the variable is immutable, then environment-cell signals an environment:immutable-location error. If SYM is unbound in ENV, signal an environment:unbound error. If you use this function, you should consider using environment-observe, to be notified when SYM gets re-bound to a new value cell, or becomes undefined.

environment-observe
 -- Scheme Procedure: environment-observe env proc
     Whenever ENV's bindings change, apply PROC to ENV. This function returns an object, token, which you can pass to environment-unobserve to remove PROC from the set of procedures observing ENV.  The type and value of token is unspecified.

environment-observe-weak
 -- Scheme Procedure: environment-observe-weak env proc
     This function is the same as environment-observe, except that the reference ENV retains to PROC is a weak reference. This means that, if there are no other live, non-weak references to PROC, it will be garbage-collected, and dropped from ENV's list of observing procedures.

environment-unobserve
 -- Scheme Procedure: environment-unobserve token
     Cancel the observation request which returned the value TOKEN.  The return value is unspecified. If a call (environment-observe env proc) returns TOKEN, then the call (environment-unobserve token) will cause PROC to no longer be called when ENV's bindings change.

make-leaf-environment
 -- Scheme Procedure: make-leaf-environment
     Create a new leaf environment, containing no bindings. All bindings and locations created in the new environment will be mutable.

leaf-environment?
 -- Scheme Procedure: leaf-environment? object
     Return #t if object is a leaf environment, or #f otherwise.

make-eval-environment
 -- Scheme Procedure: make-eval-environment local imported
     Return a new environment object eval whose bindings are the union of the bindings in the environments LOCAL and IMPORTED, with bindings from LOCAL taking precedence. Definitions made in eval are placed in LOCAL. Applying environment-define or environment-undefine to eval has the same effect as applying the procedure to LOCAL. Note that eval incorporates LOCAL and IMPORTED by reference: If, after creating eval, the program changes the bindings of LOCAL or IMPORTED, those changes will be visible in eval. Since most Scheme evaluation takes place in eval environments, they transparently cache the bindings received from LOCAL and IMPORTED. Thus, the first time the program looks up a symbol in eval, eval may make calls to LOCAL or IMPORTED to find their bindings, but subsequent references to that symbol will be as fast as references to bindings in finite environments. In typical use, LOCAL will be a finite environment, and IMPORTED will be an import environment

eval-environment?
 -- Scheme Procedure: eval-environment? object
     Return #t if object is an eval environment, or #f otherwise.

eval-environment-local
 -- Scheme Procedure: eval-environment-local env
     Return the local environment of eval environment ENV.

eval-environment-set-local!
 -- Scheme Procedure: eval-environment-set-local! env local
     Change ENV's local environment to LOCAL.

eval-environment-imported
 -- Scheme Procedure: eval-environment-imported env
     Return the imported environment of eval environment ENV.

eval-environment-set-imported!
 -- Scheme Procedure: eval-environment-set-imported! env imported
     Change ENV's imported environment to IMPORTED.

make-import-environment
 -- Scheme Procedure: make-import-environment imports conflict_proc
     Return a new environment IMP whose bindings are the union of the bindings from the environments in IMPORTS; IMPORTS must be a list of environments. That is, IMP binds a symbol to a location when some element of IMPORTS does. If two different elements of IMPORTS have a binding for the same symbol, the CONFLICT-PROC is called with the following parameters:  the import environment, the symbol and the list of the imported environments that bind the symbol. If the CONFLICT-PROC returns an environment ENV, the conflict is considered as resolved and the binding from ENV is used.  If the CONFLICT-PROC returns some non-environment object, the conflict is considered unresolved and the symbol is treated as unspecified in the import environment. The checking for conflicts may be performed lazily, i. e. at the moment when a value or binding for a certain symbol is requested instead of the moment when the environment is created or the bindings of the imports change. All bindings in IMP are immutable. If you apply environment-define or environment-undefine to IMP, Guile will signal an environment:immutable-binding error. However, notice that the set of bindings in IMP may still change, if one of its imported environments changes.

import-environment?
 -- Scheme Procedure: import-environment? object
     Return #t if object is an import environment, or #f otherwise.

import-environment-imports
 -- Scheme Procedure: import-environment-imports env
     Return the list of environments imported by the import environment ENV.

import-environment-set-imports!
 -- Scheme Procedure: import-environment-set-imports! env imports
     Change ENV's list of imported environments to IMPORTS, and check for conflicts.

make-export-environment
 -- Scheme Procedure: make-export-environment private signature
     Return a new environment EXP containing only those bindings in private whose symbols are present in SIGNATURE. The PRIVATE argument must be an environment.

     The environment EXP binds symbol to location when ENV does, and symbol is exported by SIGNATURE.

     SIGNATURE is a list specifying which of the bindings in PRIVATE should be visible in EXP. Each element of SIGNATURE should be a list of the form: (symbol attribute ...) where each attribute is one of the following:

     the symbol mutable-location
          EXP should treat the location bound to symbol as mutable. That is, EXP will pass calls to environment-set! or environment-cell directly through to private.

     the symbol immutable-location
          EXP should treat the location bound to symbol as immutable. If the program applies environment-set! to EXP and symbol, or calls environment-cell to obtain a writable value cell, environment-set! will signal an environment:immutable-location error. Note that, even if an export environment treats a location as immutable, the underlying environment may treat it as mutable, so its value may change.

     It is an error for an element of signature to specify both mutable-location and immutable-location. If neither is specified, immutable-location is assumed.

     As a special case, if an element of signature is a lone symbol SYM, it is equivalent to an element of the form (sym).

     All bindings in EXP are immutable. If you apply environment-define or environment-undefine to EXP, Guile will signal an environment:immutable-binding error. However, notice that the set of bindings in EXP may still change, if the bindings in private change.

export-environment?
 -- Scheme Procedure: export-environment? object
     Return #t if object is an export environment, or #f otherwise.

export-environment-private
 -- Scheme Procedure: export-environment-private env
     Return the private environment of export environment ENV.

export-environment-set-private!
 -- Scheme Procedure: export-environment-set-private! env private
     Change the private environment of export environment ENV.

export-environment-signature
 -- Scheme Procedure: export-environment-signature env
     Return the signature of export environment ENV.

export-environment-set-signature!
 -- Scheme Procedure: export-environment-set-signature! env signature
     Change the signature of export environment ENV.

eq?
 -- Scheme Procedure: eq? x y
     Return #t iff X references the same object as Y. eq? is similar to eqv? except that in some cases it is capable of discerning distinctions finer than those detectable by eqv?.

eqv?
 -- Scheme Procedure: eqv? x y
     The eqv? procedure defines a useful equivalence relation on objects. Briefly, it returns #t if X and Y should normally be regarded as the same object.  This relation is left slightly open to interpretation, but works for comparing immediate integers, characters, and inexact numbers.

equal?
 -- Scheme Procedure: equal? x y
     Return #t iff X and Y are recursively eqv? equivalent. equal? recursively compares the contents of pairs, vectors, and strings, applying eqv? on other objects such as numbers and symbols.  A rule of thumb is that objects are generally equal?  if they print the same.  equal? may fail to terminate if its arguments are circular data structures.

scm-error
 -- Scheme Procedure: scm-error key subr message args data
     Raise an error with key KEY.  SUBR can be a string naming the procedure associated with the error, or #f. MESSAGE is the error message string, possibly containing ~S and ~A escapes.  When an error is reported, these are replaced by formatting the corresponding members of ARGS: ~A (was %s in older versions of Guile) formats using display and ~S (was %S) formats using write.  DATA is a list or #f depending on KEY: if KEY is system-error then it should be a list containing the Unix errno value; If KEY is signal then it should be a list containing the Unix signal number; otherwise it will usually be #f.

strerror
 -- Scheme Procedure: strerror err
     Return the Unix error message corresponding to ERR, which must be an integer value.

apply:nconc2last
 -- Scheme Procedure: apply:nconc2last lst
     Given a list (ARG1 ... ARGS), this function conses the ARG1 ... arguments onto the front of ARGS, and returns the resulting list. Note that ARGS is a list; thus, the argument to this function is a list whose last element is a list. Note: Rather than do new consing, apply:nconc2last destroys its argument, so use with care.

force
 -- Scheme Procedure: force x
     If the promise X has not been computed yet, compute and return X, otherwise just return the previously computed value.

promise?
 -- Scheme Procedure: promise? obj
     Return true if OBJ is a promise, i.e. a delayed computation (see Delayed evaluation (The Revised^5 Report on Scheme)).

cons-source
 -- Scheme Procedure: cons-source xorig x y
     Create and return a new pair whose car and cdr are X and Y. Any source properties associated with XORIG are also associated with the new pair.

copy-tree
 -- Scheme Procedure: copy-tree obj
     Recursively copy the data tree that is bound to OBJ, and return a pointer to the new data structure.  copy-tree recurses down the contents of both pairs and vectors (since both cons cells and vector cells may point to arbitrary objects), and stops recursing when it hits any other object.

primitive-eval
 -- Scheme Procedure: primitive-eval exp
     Evaluate EXP in the top-level environment specified by the current module.

eval
 -- Scheme Procedure: eval exp module
     Evaluate EXP, a list representing a Scheme expression, in the top-level environment specified by MODULE. While EXP is evaluated (using primitive-eval), MODULE is made the current module.  The current module is reset to its previous value when EVAL returns.

eval2
 -- Scheme Procedure: eval2 obj env_thunk
     Evaluate EXP, a Scheme expression, in the environment designated by LOOKUP, a symbol-lookup function. Do not use this version of eval, it does not play well with the module system.  Use eval or primitive-eval instead.

eval-options-interface
 -- Scheme Procedure: eval-options-interface [setting]
     Option interface for the evaluation options. Instead of using this procedure directly, use the procedures eval-enable, eval-disable, eval-set! and eval-options.

evaluator-traps-interface
 -- Scheme Procedure: evaluator-traps-interface [setting]
     Option interface for the evaluator trap options.

defined?
 -- Scheme Procedure: defined? sym [env]
     Return #t if SYM is defined in the lexical environment ENV.  When ENV is not specified, look in the top-level environment as defined by the current module.

map-in-order
 -- Scheme Procedure: map-in-order
     implemented by the C function "scm_map"

self-evaluating?
 -- Scheme Procedure: self-evaluating? obj
     Return #t for objects which Guile considers self-evaluating

load-extension
 -- Scheme Procedure: load-extension lib init
     Load and initialize the extension designated by LIB and INIT. When there is no pre-registered function for LIB/INIT, this is equivalent to

          (dynamic-call INIT (dynamic-link LIB))

     When there is a pre-registered function, that function is called instead.

     Normally, there is no pre-registered function.  This option exists only for situations where dynamic linking is unavailable or unwanted. In that case, you would statically link your program with the desired library, and register its init function right after Guile has been initialized.

     LIB should be a string denoting a shared library without any file type suffix such as ".so".  The suffix is provided automatically.  It should also not contain any directory components.  Libraries that implement Guile Extensions should be put into the normal locations for shared libraries.  We recommend to use the naming convention libguile-bla-blum for a extension related to a module `(bla blum)'.

     The normal way for a extension to be used is to write a small Scheme file that defines a module, and to load the extension into this module.  When the module is auto-loaded, the extension is loaded as well.  For example,

          (define-module (bla blum))

          (load-extension "libguile-bla-blum" "bla_init_blum")

program-arguments
 -- Scheme Procedure: program-arguments
 -- Scheme Procedure: command-line
     Return the list of command line arguments passed to Guile, as a list of strings.  The list includes the invoked program name, which is usually "guile", but excludes switches and parameters for command line options like -e and -l.

make-fluid
 -- Scheme Procedure: make-fluid
     Return a newly created fluid. Fluids are objects of a certain type (a smob) that can hold one SCM value per dynamic root.  That is, modifications to this value are only visible to code that executes within the same dynamic root as the modifying code.  When a new dynamic root is constructed, it inherits the values from its parent.  Because each thread executes in its own dynamic root, you can use fluids for thread local storage.

fluid?
 -- Scheme Procedure: fluid? obj
     Return #t iff OBJ is a fluid; otherwise, return #f.

fluid-ref
 -- Scheme Procedure: fluid-ref fluid
     Return the value associated with FLUID in the current dynamic root.  If FLUID has not been set, then return #f.

fluid-set!
 -- Scheme Procedure: fluid-set! fluid value
     Set the value associated with FLUID in the current dynamic root.

with-fluids*
 -- Scheme Procedure: with-fluids* fluids values thunk
     Set FLUIDS to VALUES temporary, and call THUNK. FLUIDS must be a list of fluids and VALUES must be the same number of their values to be applied.  Each substitution is done one after another.  THUNK must be a procedure with no argument.

setvbuf
 -- Scheme Procedure: setvbuf port mode [size]
     Set the buffering mode for PORT.  MODE can be:

     _IONBF
          non-buffered

     _IOLBF
          line buffered

     _IOFBF
          block buffered, using a newly allocated buffer of SIZE bytes. If SIZE is omitted, a default size will be used.

file-port?
 -- Scheme Procedure: file-port? obj
     Determine whether OBJ is a port that is related to a file.

open-file
 -- Scheme Procedure: open-file filename mode
     Open the file whose name is FILENAME, and return a port representing that file.  The attributes of the port are determined by the MODE string.  The way in which this is interpreted is similar to C stdio.  The first character must be one of the following:

     r
          Open an existing file for input.

     w
          Open a file for output, creating it if it doesn't already exist or removing its contents if it does.

     a
          Open a file for output, creating it if it doesn't already exist.  All writes to the port will go to the end of the file. The "append mode" can be turned off while the port is in use see fcntl

     The following additional characters can be appended:

     +
          Open the port for both input and output.  E.g., r+: open an existing file for both input and output.

     0
          Create an "unbuffered" port.  In this case input and output operations are passed directly to the underlying port implementation without additional buffering.  This is likely to slow down I/O operations.  The buffering mode can be changed while a port is in use see setvbuf

     l
          Add line-buffering to the port.  The port output buffer will be automatically flushed whenever a newline character is written.

     In theory we could create read/write ports which were buffered in one direction only.  However this isn't included in the current interfaces.  If a file cannot be opened with the access requested, open-file throws an exception.

gc-stats
 -- Scheme Procedure: gc-stats
     Return an association list of statistics about Guile's current use of storage.

object-address
 -- Scheme Procedure: object-address obj
     Return an integer that for the lifetime of OBJ is uniquely returned by this function for OBJ

gc
 -- Scheme Procedure: gc
     Scans all of SCM objects and reclaims for further use those that are no longer accessible.

%compute-slots
 -- Scheme Procedure: %compute-slots class
     Return a list consisting of the names of all slots belonging to class CLASS, i. e. the slots of CLASS and of all of its superclasses.

get-keyword
 -- Scheme Procedure: get-keyword key l default_value
     Determine an associated value for the keyword KEY from the list L.  The list L has to consist of an even number of elements, where, starting with the first, every second element is a keyword, followed by its associated value. If L does not hold a value for KEY, the value DEFAULT_VALUE is returned.

%initialize-object
 -- Scheme Procedure: %initialize-object obj initargs
     Initialize the object OBJ with the given arguments INITARGS.

%prep-layout!
 -- Scheme Procedure: %prep-layout! class

%inherit-magic!
 -- Scheme Procedure: %inherit-magic! class dsupers

instance?
 -- Scheme Procedure: instance? obj
     Return #t if OBJ is an instance.

class-name
 -- Scheme Procedure: class-name obj
     Return the class name of OBJ.

class-direct-supers
 -- Scheme Procedure: class-direct-supers obj
     Return the direct superclasses of the class OBJ.

class-direct-slots
 -- Scheme Procedure: class-direct-slots obj
     Return the direct slots of the class OBJ.

class-direct-subclasses
 -- Scheme Procedure: class-direct-subclasses obj
     Return the direct subclasses of the class OBJ.

class-direct-methods
 -- Scheme Procedure: class-direct-methods obj
     Return the direct methods of the class OBJ

class-precedence-list
 -- Scheme Procedure: class-precedence-list obj
     Return the class precedence list of the class OBJ.

class-slots
 -- Scheme Procedure: class-slots obj
     Return the slot list of the class OBJ.

class-environment
 -- Scheme Procedure: class-environment obj
     Return the environment of the class OBJ.

generic-function-name
 -- Scheme Procedure: generic-function-name obj
     Return the name of the generic function OBJ.

generic-function-methods
 -- Scheme Procedure: generic-function-methods obj
     Return the methods of the generic function OBJ.

method-generic-function
 -- Scheme Procedure: method-generic-function obj
     Return the generic function for the method OBJ.

method-specializers
 -- Scheme Procedure: method-specializers obj
     Return specializers of the method OBJ.

method-procedure
 -- Scheme Procedure: method-procedure obj
     Return the procedure of the method OBJ.

accessor-method-slot-definition
 -- Scheme Procedure: accessor-method-slot-definition obj
     Return the slot definition of the accessor OBJ.

%tag-body
 -- Scheme Procedure: %tag-body body
     Internal GOOPS magic---don't use this function!

make-unbound
 -- Scheme Procedure: make-unbound
     Return the unbound value.

unbound?
 -- Scheme Procedure: unbound? obj
     Return #t if OBJ is unbound.

assert-bound
 -- Scheme Procedure: assert-bound value obj
     Return VALUE if it is bound, and invoke the SLOT-UNBOUND method of OBJ if it is not.

@assert-bound-ref
 -- Scheme Procedure: @assert-bound-ref obj index
     Like assert-bound, but use INDEX for accessing the value from OBJ.

%fast-slot-ref
 -- Scheme Procedure: %fast-slot-ref obj index
     Return the slot value with index INDEX from OBJ.

%fast-slot-set!
 -- Scheme Procedure: %fast-slot-set! obj index value
     Set the slot with index INDEX in OBJ to VALUE.

slot-ref-using-class
 -- Scheme Procedure: slot-ref-using-class class obj slot_name

slot-set-using-class!
 -- Scheme Procedure: slot-set-using-class! class obj slot_name value

slot-bound-using-class?
 -- Scheme Procedure: slot-bound-using-class? class obj slot_name

slot-exists-using-class?
 -- Scheme Procedure: slot-exists-using-class? class obj slot_name

slot-ref
 -- Scheme Procedure: slot-ref obj slot_name
     Return the value from OBJ's slot with the name SLOT_NAME.

slot-set!
 -- Scheme Procedure: slot-set! obj slot_name value
     Set the slot named SLOT_NAME of OBJ to VALUE.

slot-bound?
 -- Scheme Procedure: slot-bound? obj slot_name
     Return #t if the slot named SLOT_NAME of OBJ is bound.

slot-exists?
 -- Scheme Procedure: slot-exists? obj slot_name
     Return #t if OBJ has a slot named SLOT_NAME.

%allocate-instance
 -- Scheme Procedure: %allocate-instance class initargs
     Create a new instance of class CLASS and initialize it from the arguments INITARGS.

%set-object-setter!
 -- Scheme Procedure: %set-object-setter! obj setter

%modify-instance
 -- Scheme Procedure: %modify-instance old new

%modify-class
 -- Scheme Procedure: %modify-class old new

%invalidate-class
 -- Scheme Procedure: %invalidate-class class

%invalidate-method-cache!
 -- Scheme Procedure: %invalidate-method-cache! gf

generic-capability?
 -- Scheme Procedure: generic-capability? proc

enable-primitive-generic!
 -- Scheme Procedure: enable-primitive-generic! . subrs

primitive-generic-generic
 -- Scheme Procedure: primitive-generic-generic subr

make
 -- Scheme Procedure: make . args
     Make a new object.  ARGS must contain the class and all necessary initialization information.

find-method
 -- Scheme Procedure: find-method . l

%method-more-specific?
 -- Scheme Procedure: %method-more-specific? m1 m2 targs

%goops-loaded
 -- Scheme Procedure: %goops-loaded
     Announce that GOOPS is loaded and perform initialization on the C level which depends on the loaded GOOPS modules.

make-guardian
 -- Scheme Procedure: make-guardian [greedy_p]
     Create a new guardian. A guardian protects a set of objects from garbage collection, allowing a program to apply cleanup or other actions.

     make-guardian returns a procedure representing the guardian. Calling the guardian procedure with an argument adds the argument to the guardian's set of protected objects. Calling the guardian procedure without an argument returns one of the protected objects which are ready for garbage collection, or #f if no such object is available. Objects which are returned in this way are removed from the guardian.

     make-guardian takes one optional argument that says whether the new guardian should be greedy or sharing.  If there is any chance that any object protected by the guardian may be resurrected, then you should make the guardian greedy (this is the default).

     See R. Kent Dybvig, Carl Bruggeman, and David Eby (1993) "Guardians in a Generation-Based Garbage Collector". ACM SIGPLAN Conference on Programming Language Design and Implementation, June 1993.

     (the semantics are slightly different at this point, but the paper still (mostly) accurately describes the interface).

guardian-destroyed?
 -- Scheme Procedure: guardian-destroyed? guardian
     Return #t if GUARDIAN has been destroyed, otherwise #f.

guardian-greedy?
 -- Scheme Procedure: guardian-greedy? guardian
     Return #t if GUARDIAN is a greedy guardian, otherwise #f.

destroy-guardian!
 -- Scheme Procedure: destroy-guardian! guardian
     Destroys GUARDIAN, by making it impossible to put any more objects in it or get any objects from it.  It also unguards any objects guarded by GUARDIAN.

hashq
 -- Scheme Procedure: hashq key size
     Determine a hash value for KEY that is suitable for lookups in a hashtable of size SIZE, where eq? is used as the equality predicate.  The function returns an integer in the range 0 to SIZE - 1.  Note that hashq may use internal addresses.  Thus two calls to hashq where the keys are eq? are not guaranteed to deliver the same value if the key object gets garbage collected in between.  This can happen, for example with symbols: (hashq 'foo n) (gc) (hashq 'foo n) may produce two different values, since foo will be garbage collected.

hashv
 -- Scheme Procedure: hashv key size
     Determine a hash value for KEY that is suitable for lookups in a hashtable of size SIZE, where eqv? is used as the equality predicate.  The function returns an integer in the range 0 to SIZE - 1.  Note that (hashv key) may use internal addresses.  Thus two calls to hashv where the keys are eqv? are not guaranteed to deliver the same value if the key object gets garbage collected in between.  This can happen, for example with symbols: (hashv 'foo n) (gc) (hashv 'foo n) may produce two different values, since foo will be garbage collected.

hash
 -- Scheme Procedure: hash key size
     Determine a hash value for KEY that is suitable for lookups in a hashtable of size SIZE, where equal? is used as the equality predicate.  The function returns an integer in the range 0 to SIZE - 1.

hashq-get-handle
 -- Scheme Procedure: hashq-get-handle table key
     This procedure returns the (key . value) pair from the hash table TABLE.  If TABLE does not hold an associated value for KEY, #f is returned. Uses eq? for equality testing.

hashq-create-handle!
 -- Scheme Procedure: hashq-create-handle! table key init
     This function looks up KEY in TABLE and returns its handle. If KEY is not already present, a new handle is created which associates KEY with INIT.

hashq-ref
 -- Scheme Procedure: hashq-ref table key [dflt]
     Look up KEY in the hash table TABLE, and return the value (if any) associated with it.  If KEY is not found, return DEFAULT (or #f if no DEFAULT argument is supplied).  Uses eq? for equality testing.

hashq-set!
 -- Scheme Procedure: hashq-set! table key val
     Find the entry in TABLE associated with KEY, and store VALUE there. Uses eq? for equality testing.

hashq-remove!
 -- Scheme Procedure: hashq-remove! table key
     Remove KEY (and any value associated with it) from TABLE.  Uses eq? for equality tests.

hashv-get-handle
 -- Scheme Procedure: hashv-get-handle table key
     This procedure returns the (key . value) pair from the hash table TABLE.  If TABLE does not hold an associated value for KEY, #f is returned. Uses eqv? for equality testing.

hashv-create-handle!
 -- Scheme Procedure: hashv-create-handle! table key init
     This function looks up KEY in TABLE and returns its handle. If KEY is not already present, a new handle is created which associates KEY with INIT.

hashv-ref
 -- Scheme Procedure: hashv-ref table key [dflt]
     Look up KEY in the hash table TABLE, and return the value (if any) associated with it.  If KEY is not found, return DEFAULT (or #f if no DEFAULT argument is supplied).  Uses eqv? for equality testing.

hashv-set!
 -- Scheme Procedure: hashv-set! table key val
     Find the entry in TABLE associated with KEY, and store VALUE there. Uses eqv? for equality testing.

hashv-remove!
 -- Scheme Procedure: hashv-remove! table key
     Remove KEY (and any value associated with it) from TABLE.  Uses eqv? for equality tests.

hash-get-handle
 -- Scheme Procedure: hash-get-handle table key
     This procedure returns the (key . value) pair from the hash table TABLE.  If TABLE does not hold an associated value for KEY, #f is returned. Uses equal? for equality testing.

hash-create-handle!
 -- Scheme Procedure: hash-create-handle! table key init
     This function looks up KEY in TABLE and returns its handle. If KEY is not already present, a new handle is created which associates KEY with INIT.

hash-ref
 -- Scheme Procedure: hash-ref table key [dflt]
     Look up KEY in the hash table TABLE, and return the value (if any) associated with it.  If KEY is not found, return DEFAULT (or #f if no DEFAULT argument is supplied).  Uses equal? for equality testing.

hash-set!
 -- Scheme Procedure: hash-set! table key val
     Find the entry in TABLE associated with KEY, and store VALUE there. Uses equal? for equality testing.

hash-remove!
 -- Scheme Procedure: hash-remove! table key
     Remove KEY (and any value associated with it) from TABLE.  Uses equal? for equality tests.

hashx-get-handle
 -- Scheme Procedure: hashx-get-handle hash assoc table key
     This behaves the same way as the corresponding -get-handle function, but uses HASH as a hash function and ASSOC to compare keys.  hash must be a function that takes two arguments, a key to be hashed and a table size.  assoc must be an associator function, like assoc, assq or assv.

hashx-create-handle!
 -- Scheme Procedure: hashx-create-handle! hash assoc table key init
     This behaves the same way as the corresponding -create-handle function, but uses HASH as a hash function and ASSOC to compare keys.  hash must be a function that takes two arguments, a key to be hashed and a table size.  assoc must be an associator function, like assoc, assq or assv.

hashx-ref
 -- Scheme Procedure: hashx-ref hash assoc table key [dflt]
     This behaves the same way as the corresponding ref function, but uses HASH as a hash function and ASSOC to compare keys.  hash must be a function that takes two arguments, a key to be hashed and a table size. assoc must be an associator function, like assoc, assq or assv.

     By way of illustration, hashq-ref table key is equivalent to hashx-ref hashq assq table key.

hashx-set!
 -- Scheme Procedure: hashx-set! hash assoc table key val
     This behaves the same way as the corresponding set! function, but uses HASH as a hash function and ASSOC to compare keys.  hash must be a function that takes two arguments, a key to be hashed and a table size. assoc must be an associator function, like assoc, assq or assv.

     By way of illustration, hashq-set! table key is equivalent to hashx-set!  hashq assq table key.

hash-fold
 -- Scheme Procedure: hash-fold proc init table
     An iterator over hash-table elements. Accumulates and returns a result by applying PROC successively. The arguments to PROC are "(key value prior-result)" where key and value are successive pairs from the hash table TABLE, and prior-result is either INIT (for the first application of PROC) or the return value of the previous application of PROC. For example, (hash-fold acons '() tab) will convert a hash table into an a-list of key-value pairs.

make-hook
 -- Scheme Procedure: make-hook [n_args]
     Create a hook for storing procedure of arity N_ARGS. N_ARGS defaults to zero.  The returned value is a hook object to be used with the other hook procedures.

hook?
 -- Scheme Procedure: hook? x
     Return #t if X is a hook, #f otherwise.

hook-empty?
 -- Scheme Procedure: hook-empty? hook
     Return #t if HOOK is an empty hook, #f otherwise.

add-hook!
 -- Scheme Procedure: add-hook! hook proc [append_p]
     Add the procedure PROC to the hook HOOK. The procedure is added to the end if APPEND_P is true, otherwise it is added to the front.  The return value of this procedure is not specified.

remove-hook!
 -- Scheme Procedure: remove-hook! hook proc
     Remove the procedure PROC from the hook HOOK.  The return value of this procedure is not specified.

reset-hook!
 -- Scheme Procedure: reset-hook! hook
     Remove all procedures from the hook HOOK.  The return value of this procedure is not specified.

run-hook
 -- Scheme Procedure: run-hook hook . args
     Apply all procedures from the hook HOOK to the arguments ARGS.  The order of the procedure application is first to last.  The return value of this procedure is not specified.

hook->list
 -- Scheme Procedure: hook->list hook
     Convert the procedure list of HOOK to a list.

ftell
 -- Scheme Procedure: ftell fd_port
     Return an integer representing the current position of FD/PORT, measured from the beginning.  Equivalent to:

          (seek port 0 SEEK_CUR)

redirect-port
 -- Scheme Procedure: redirect-port old new
     This procedure takes two ports and duplicates the underlying file descriptor from OLD-PORT into NEW-PORT.  The current file descriptor in NEW-PORT will be closed. After the redirection the two ports will share a file position and file status flags.

     The return value is unspecified.

     Unexpected behaviour can result if both ports are subsequently used and the original and/or duplicate ports are buffered.

     This procedure does not have any side effects on other ports or revealed counts.

dup->fdes
 -- Scheme Procedure: dup->fdes fd_or_port [fd]
     Return a new integer file descriptor referring to the open file designated by FD_OR_PORT, which must be either an open file port or a file descriptor.

dup2
 -- Scheme Procedure: dup2 oldfd newfd
     A simple wrapper for the dup2 system call. Copies the file descriptor OLDFD to descriptor number NEWFD, replacing the previous meaning of NEWFD.  Both OLDFD and NEWFD must be integers. Unlike for dup->fdes or primitive-move->fdes, no attempt is made to move away ports which are using NEWFD. The return value is unspecified.

fileno
 -- Scheme Procedure: fileno port
     Return the integer file descriptor underlying PORT.  Does not change its revealed count.

isatty?
 -- Scheme Procedure: isatty? port
     Return #t if PORT is using a serial non--file device, otherwise #f.

fdopen
 -- Scheme Procedure: fdopen fdes modes
     Return a new port based on the file descriptor FDES. Modes are given by the string MODES.  The revealed count of the port is initialized to zero.  The modes string is the same as that accepted by open-file.

primitive-move->fdes
 -- Scheme Procedure: primitive-move->fdes port fd
     Moves the underlying file descriptor for PORT to the integer value FDES without changing the revealed count of PORT. Any other ports already using this descriptor will be automatically shifted to new descriptors and their revealed counts reset to zero. The return value is #f if the file descriptor already had the required value or #t if it was moved.

fdes->ports
 -- Scheme Procedure: fdes->ports fd
     Return a list of existing ports which have FDES as an underlying file descriptor, without changing their revealed counts.

make-keyword-from-dash-symbol
 -- Scheme Procedure: make-keyword-from-dash-symbol symbol
     Make a keyword object from a SYMBOL that starts with a dash.

keyword?
 -- Scheme Procedure: keyword? obj
     Return #t if the argument OBJ is a keyword, else #f.

keyword-dash-symbol
 -- Scheme Procedure: keyword-dash-symbol keyword
     Return the dash symbol for KEYWORD. This is the inverse of make-keyword-from-dash-symbol.

nil-cons
 -- Scheme Procedure: nil-cons x y
     Create a new cons cell with X as the car and Y as the cdr, but convert Y to Scheme's end-of-list if it is a LISP nil.

nil-car
 -- Scheme Procedure: nil-car x
     Return the car of X, but convert it to LISP nil if it is Scheme's end-of-list.

nil-cdr
 -- Scheme Procedure: nil-cdr x
     Return the cdr of X, but convert it to LISP nil if it is Scheme's end-of-list.

null
 -- Scheme Procedure: null x
     Return LISP's t if X is nil in the LISP sense, return LISP's nil otherwise.

nil-eq
 -- Scheme Procedure: nil-eq x y
     Compare X and Y and return LISP's t if they are eq?, return LISP's nil otherwise.

list
 -- Scheme Procedure: list . objs
     Return a list containing OBJS, the arguments to list.

list*
 -- Scheme Procedure: list*
     implemented by the C function "scm_cons_star"

cons*
 -- Scheme Procedure: cons* arg . rest
     Like list, but the last arg provides the tail of the constructed list, returning (cons ARG1 (cons ARG2 (cons ... ARGN))).  Requires at least one argument.  If given one argument, that argument is returned as result.  This function is called list* in some other Schemes and in Common LISP.

null?
 -- Scheme Procedure: null? x
     Return #t iff X is the empty list, else #f.

list?
 -- Scheme Procedure: list? x
     Return #t iff X is a proper list, else #f.

length
 -- Scheme Procedure: length lst
     Return the number of elements in list LST.

append
 -- Scheme Procedure: append . args
     Return a list consisting of the elements the lists passed as arguments.

          (append '(x) '(y))          =>  (x y)
          (append '(a) '(b c d))      =>  (a b c d)
          (append '(a (b)) '((c)))    =>  (a (b) (c))

     The resulting list is always newly allocated, except that it shares structure with the last list argument.  The last argument may actually be any object; an improper list results if the last argument is not a proper list.

          (append '(a b) '(c . d))    =>  (a b c . d)
          (append '() 'a)             =>  a

append!
 -- Scheme Procedure: append! . lists
     A destructive version of append (see Pairs and Lists (The Revised^5 Report on Scheme)).  The cdr field of each list's final pair is changed to point to the head of the next list, so no consing is performed.  Return a pointer to the mutated list.

last-pair
 -- Scheme Procedure: last-pair lst
     Return a pointer to the last pair in LST, signalling an error if LST is circular.

reverse
 -- Scheme Procedure: reverse lst
     Return a new list that contains the elements of LST but in reverse order.

reverse!
 -- Scheme Procedure: reverse! lst [new_tail]
     A destructive version of reverse (see Pairs and Lists (The Revised^5 Report on Scheme)).  The cdr of each cell in LST is modified to point to the previous list element.  Return a pointer to the head of the reversed list.

     Caveat: because the list is modified in place, the tail of the original list now becomes its head, and the head of the original list now becomes the tail.  Therefore, the LST symbol to which the head of the original list was bound now points to the tail.  To ensure that the head of the modified list is not lost, it is wise to save the return value of reverse!

list-ref
 -- Scheme Procedure: list-ref list k
     Return the Kth element from LIST.

list-set!
 -- Scheme Procedure: list-set! list k val
     Set the Kth element of LIST to VAL.

list-cdr-ref
 -- Scheme Procedure: list-cdr-ref
     implemented by the C function "scm_list_tail"

list-tail
 -- Scheme Procedure: list-tail lst k
 -- Scheme Procedure: list-cdr-ref lst k
     Return the "tail" of LST beginning with its Kth element. The first element of the list is considered to be element 0.

     list-tail and list-cdr-ref are identical.  It may help to think of list-cdr-ref as accessing the Kth cdr of the list, or returning the results of cdring K times down LST.

list-cdr-set!
 -- Scheme Procedure: list-cdr-set! list k val
     Set the Kth cdr of LIST to VAL.

list-head
 -- Scheme Procedure: list-head lst k
     Copy the first K elements from LST into a new list, and return it.

list-copy
 -- Scheme Procedure: list-copy lst
     Return a (newly-created) copy of LST.

sloppy-memq
 -- Scheme Procedure: sloppy-memq x lst
     This procedure behaves like memq, but does no type or error checking. Its use is recommended only in writing Guile internals, not for high-level Scheme programs.

sloppy-memv
 -- Scheme Procedure: sloppy-memv x lst
     This procedure behaves like memv, but does no type or error checking. Its use is recommended only in writing Guile internals, not for high-level Scheme programs.

sloppy-member
 -- Scheme Procedure: sloppy-member x lst
     This procedure behaves like member, but does no type or error checking. Its use is recommended only in writing Guile internals, not for high-level Scheme programs.

memq
 -- Scheme Procedure: memq x lst
     Return the first sublist of LST whose car is eq? to X where the sublists of LST are the non-empty lists returned by (list-tail LST K) for K less than the length of LST.  If X does not occur in LST, then #f (not the empty list) is returned.

memv
 -- Scheme Procedure: memv x lst
     Return the first sublist of LST whose car is eqv? to X where the sublists of LST are the non-empty lists returned by (list-tail LST K) for K less than the length of LST.  If X does not occur in LST, then #f (not the empty list) is returned.

member
 -- Scheme Procedure: member x lst
     Return the first sublist of LST whose car is equal? to X where the sublists of LST are the non-empty lists returned by (list-tail LST K) for K less than the length of LST.  If X does not occur in LST, then #f (not the empty list) is returned.

delq!
 -- Scheme Procedure: delq! item lst
 -- Scheme Procedure: delv! item lst
 -- Scheme Procedure: delete! item lst
     These procedures are destructive versions of delq, delv and delete: they modify the pointers in the existing LST rather than creating a new list.  Caveat evaluator: Like other destructive list functions, these functions cannot modify the binding of LST, and so cannot be used to delete the first element of LST destructively.

delv!
 -- Scheme Procedure: delv! item lst
     Destructively remove all elements from LST that are eqv? to ITEM.

delete!
 -- Scheme Procedure: delete! item lst
     Destructively remove all elements from LST that are equal? to ITEM.

delq
 -- Scheme Procedure: delq item lst
     Return a newly-created copy of LST with elements eq? to ITEM removed.  This procedure mirrors memq: delq compares elements of LST against ITEM with eq?.

delv
 -- Scheme Procedure: delv item lst
     Return a newly-created copy of LST with elements eqv?  to ITEM removed.  This procedure mirrors memv: delv compares elements of LST against ITEM with eqv?.

delete
 -- Scheme Procedure: delete item lst
     Return a newly-created copy of LST with elements equal?  to ITEM removed.  This procedure mirrors member: delete compares elements of LST against ITEM with equal?.

delq1!
 -- Scheme Procedure: delq1! item lst
     Like delq!, but only deletes the first occurrence of ITEM from LST.  Tests for equality using eq?.  See also delv1! and delete1!.

delv1!
 -- Scheme Procedure: delv1! item lst
     Like delv!, but only deletes the first occurrence of ITEM from LST.  Tests for equality using eqv?.  See also delq1! and delete1!.

delete1!
 -- Scheme Procedure: delete1! item lst
     Like delete!, but only deletes the first occurrence of ITEM from LST.  Tests for equality using equal?.  See also delq1! and delv1!.

primitive-load
 -- Scheme Procedure: primitive-load filename
     Load the file named FILENAME and evaluate its contents in the top-level environment. The load paths are not searched; FILENAME must either be a full pathname or be a pathname relative to the current directory.  If the  variable %load-hook is defined, it should be bound to a procedure that will be called before any code is loaded.  See the documentation for %load-hook later in this section.

%package-data-dir
 -- Scheme Procedure: %package-data-dir
     Return the name of the directory where Scheme packages, modules and libraries are kept.  On most Unix systems, this will be /usr/local/share/guile.

%library-dir
 -- Scheme Procedure: %library-dir
     Return the directory where the Guile Scheme library files are installed. E.g., may return "/usr/share/guile/1.3.5".

%site-dir
 -- Scheme Procedure: %site-dir
     Return the directory where the Guile site files are installed. E.g., may return "/usr/share/guile/site".

parse-path
 -- Scheme Procedure: parse-path path [tail]
     Parse PATH, which is expected to be a colon-separated string, into a list and return the resulting list with TAIL appended. If PATH is #f, TAIL is returned.

search-path
 -- Scheme Procedure: search-path path filename [extensions]
     Search PATH for a directory containing a file named FILENAME. The file must be readable, and not a directory. If we find one, return its full filename; otherwise, return #f.  If FILENAME is absolute, return it unchanged. If given, EXTENSIONS is a list of strings; for each directory in PATH, we search for FILENAME concatenated with each EXTENSION.

%search-load-path
 -- Scheme Procedure: %search-load-path filename
     Search %LOAD-PATH for the file named FILENAME, which must be readable by the current user.  If FILENAME is found in the list of paths to search or is an absolute pathname, return its full pathname.  Otherwise, return #f.  Filenames may have any of the optional extensions in the %load-extensions list; %search-load-path will try each extension automatically.

primitive-load-path
 -- Scheme Procedure: primitive-load-path filename
     Search %LOAD-PATH for the file named FILENAME and load it into the top-level environment.  If FILENAME is a relative pathname and is not found in the list of search paths, an error is signalled.

read-and-eval!
 -- Scheme Procedure: read-and-eval! [port]
     Read a form from PORT (standard input by default), and evaluate it (memoizing it in the process) in the top-level environment.  If no data is left to be read from PORT, an end-of-file error is signalled.

procedure->syntax
 -- Scheme Procedure: procedure->syntax code
     Return a macro which, when a symbol defined to this value appears as the first symbol in an expression, returns the result of applying CODE to the expression and the environment.

procedure->macro
 -- Scheme Procedure: procedure->macro code
     Return a macro which, when a symbol defined to this value appears as the first symbol in an expression, evaluates the result of applying CODE to the expression and the environment.  For example:

          (define trace
            (procedure->macro
             (lambda (x env) `(set! ,(cadr x) (tracef ,(cadr x) ',(cadr x))))))

          (trace foo) == (set! foo (tracef foo 'foo)).

procedure->memoizing-macro
 -- Scheme Procedure: procedure->memoizing-macro code
     Return a macro which, when a symbol defined to this value appears as the first symbol in an expression, evaluates the result of applying CODE to the expression and the environment.

     procedure->memoizing-macro is the same as procedure->macro, except that the expression returned by CODE replaces the original macro expression in the memoized form of the containing code.

macro?
 -- Scheme Procedure: macro? obj
     Return #t if OBJ is a regular macro, a memoizing macro or a syntax transformer.

macro-type
 -- Scheme Procedure: macro-type m
     Return one of the symbols syntax, macro or macro!, depending on whether M is a syntax transformer, a regular macro, or a memoizing macro, respectively.  If M is not a macro, #f is returned.

macro-name
 -- Scheme Procedure: macro-name m
     Return the name of the macro M.

macro-transformer
 -- Scheme Procedure: macro-transformer m
     Return the transformer of the macro M.

current-module
 -- Scheme Procedure: current-module
     Return the current module.

set-current-module
 -- Scheme Procedure: set-current-module module
     Set the current module to MODULE and return the previous current module.

interaction-environment
 -- Scheme Procedure: interaction-environment
     Return a specifier for the environment that contains implementation--defined bindings, typically a superset of those listed in the report.  The intent is that this procedure will return the environment in which the implementation would evaluate expressions dynamically typed by the user.

env-module
 -- Scheme Procedure: env-module env
     Return the module of ENV, a lexical environment.

standard-eval-closure
 -- Scheme Procedure: standard-eval-closure module
     Return an eval closure for the module MODULE.

standard-interface-eval-closure
 -- Scheme Procedure: standard-interface-eval-closure module
     Return a interface eval closure for the module MODULE. Such a closure does not allow new bindings to be added.

%get-pre-modules-obarray
 -- Scheme Procedure: %get-pre-modules-obarray
     Return the obarray that is used for all new bindings before the module system is booted.  The first call to set-current-module will boot the module system.

exact?
 -- Scheme Procedure: exact? x
     Return #t if X is an exact number, #f otherwise.

odd?
 -- Scheme Procedure: odd? n
     Return #t if N is an odd number, #f otherwise.

even?
 -- Scheme Procedure: even? n
     Return #t if N is an even number, #f otherwise.

logand
 -- Scheme Procedure: logand n1 n2
     Return the bitwise AND of the integer arguments.

          (logand) => -1
          (logand 7) => 7
          (logand #b111 #b011 #b001) => 1

logior
 -- Scheme Procedure: logior n1 n2
     Return the bitwise OR of the integer arguments.

          (logior) => 0
          (logior 7) => 7
          (logior #b000 #b001 #b011) => 3

logxor
 -- Scheme Procedure: logxor n1 n2
     Return the bitwise XOR of the integer arguments.  A bit is set in the result if it is set in an odd number of arguments.

          (logxor) => 0
          (logxor 7) => 7
          (logxor #b000 #b001 #b011) => 2
          (logxor #b000 #b001 #b011 #b011) => 1

logtest
 -- Scheme Procedure: logtest j k

          (logtest j k) == (not (zero? (logand j k)))

          (logtest #b0100 #b1011) => #f
          (logtest #b0100 #b0111) => #t

logbit?
 -- Scheme Procedure: logbit? index j

          (logbit? index j) == (logtest (integer-expt 2 index) j)

          (logbit? 0 #b1101) => #t
          (logbit? 1 #b1101) => #f
          (logbit? 2 #b1101) => #t
          (logbit? 3 #b1101) => #t
          (logbit? 4 #b1101) => #f

lognot
 -- Scheme Procedure: lognot n
     Return the integer which is the ones-complement of the integer argument.

          (number->string (lognot #b10000000) 2)
             => "-10000001"
          (number->string (lognot #b0) 2)
             => "-1"

integer-expt
 -- Scheme Procedure: integer-expt n k
     Return N raised to the non-negative integer exponent K.

          (integer-expt 2 5)
             => 32
          (integer-expt -3 3)
             => -27

ash
 -- Scheme Procedure: ash n cnt
     The function ash performs an arithmetic shift left by CNT bits (or shift right, if CNT is negative).  'Arithmetic' means, that the function does not guarantee to keep the bit structure of N, but rather guarantees that the result will always be rounded towards minus infinity.  Therefore, the results of ash and a corresponding bitwise shift will differ if N is negative.

     Formally, the function returns an integer equivalent to (inexact->exact (floor (* N (expt 2 CNT)))).

          (number->string (ash #b1 3) 2)     => "1000"
          (number->string (ash #b1010 -1) 2) => "101"

bit-extract
 -- Scheme Procedure: bit-extract n start end
     Return the integer composed of the START (inclusive) through END (exclusive) bits of N.  The STARTth bit becomes the 0-th bit in the result.

          (number->string (bit-extract #b1101101010 0 4) 2)
             => "1010"
          (number->string (bit-extract #b1101101010 4 9) 2)
             => "10110"

logcount
 -- Scheme Procedure: logcount n
     Return the number of bits in integer N.  If integer is positive, the 1-bits in its binary representation are counted. If negative, the 0-bits in its two's-complement binary representation are counted.  If 0, 0 is returned.

          (logcount #b10101010)
             => 4
          (logcount 0)
             => 0
          (logcount -2)
             => 1

integer-length
 -- Scheme Procedure: integer-length n
     Return the number of bits necessary to represent N.

          (integer-length #b10101010)
             => 8
          (integer-length 0)
             => 0
          (integer-length #b1111)
             => 4

number->string
 -- Scheme Procedure: number->string n [radix]
     Return a string holding the external representation of the number N in the given RADIX.  If N is inexact, a radix of 10 will be used.

string->number
 -- Scheme Procedure: string->number string [radix]
     Return a number of the maximally precise representation expressed by the given STRING. RADIX must be an exact integer, either 2, 8, 10, or 16. If supplied, RADIX is a default radix that may be overridden by an explicit radix prefix in STRING (e.g. "#o177"). If RADIX is not supplied, then the default radix is 10. If string is not a syntactically valid notation for a number, then string->number returns #f.

number?
 -- Scheme Procedure: number?
     implemented by the C function "scm_number_p"

complex?
 -- Scheme Procedure: complex? x
     Return #t if X is a complex number, #f otherwise.  Note that the sets of real, rational and integer values form subsets of the set of complex numbers, i. e. the predicate will also be fulfilled if X is a real, rational or integer number.

real?
 -- Scheme Procedure: real?
     implemented by the C function "scm_real_p"

rational?
 -- Scheme Procedure: rational? x
     Return #t if X is a rational number, #f otherwise.  Note that the set of integer values forms a subset of the set of rational numbers, i. e. the predicate will also be fulfilled if X is an integer number.  Real numbers will also satisfy this predicate, because of their limited precision.

integer?
 -- Scheme Procedure: integer? x
     Return #t if X is an integer number, #f else.

inexact?
 -- Scheme Procedure: inexact? x
     Return #t if X is an inexact number, #f else.

truncate
 -- Scheme Procedure: truncate x
     Round the inexact number X towards zero.

round
 -- Scheme Procedure: round x
     Round the number X towards the nearest integer. When it is exactly halfway between two integers, round towards the even one.

floor
 -- Scheme Procedure: floor x
     Round the number X towards minus infinity.

ceiling
 -- Scheme Procedure: ceiling x
     Round the number X towards infinity.

$expt
 -- Scheme Procedure: $expt x y
     Return X raised to the power of Y. This procedure does not accept complex arguments.

$atan2
 -- Scheme Procedure: $atan2 x y
     Return the arc tangent of the two arguments X and Y. This is similar to calculating the arc tangent of X / Y, except that the signs of both arguments are used to determine the quadrant of the result. This procedure does not accept complex arguments.

make-rectangular
 -- Scheme Procedure: make-rectangular real imaginary
     Return a complex number constructed of the given REAL and IMAGINARY parts.

make-polar
 -- Scheme Procedure: make-polar x y
     Return the complex number X * e^(i * Y).

inexact->exact
 -- Scheme Procedure: inexact->exact z
     Return an exact number that is numerically closest to Z.

class-of
 -- Scheme Procedure: class-of x
     Return the class of X.

entity?
 -- Scheme Procedure: entity? obj
     Return #t if OBJ is an entity.

operator?
 -- Scheme Procedure: operator? obj
     Return #t if OBJ is an operator.

valid-object-procedure?
 -- Scheme Procedure: valid-object-procedure? proc
     Return #t iff PROC is a procedure that can be used with set-object-procedure.  It is always valid to use a closure constructed by lambda.

set-object-procedure!
 -- Scheme Procedure: set-object-procedure! obj proc
     Set the object procedure of OBJ to PROC. OBJ must be either an entity or an operator.

make-class-object
 -- Scheme Procedure: make-class-object metaclass layout
     Create a new class object of class METACLASS, with the slot layout specified by LAYOUT.

make-subclass-object
 -- Scheme Procedure: make-subclass-object class layout
     Create a subclass object of CLASS, with the slot layout specified by LAYOUT.

object-properties
 -- Scheme Procedure: object-properties obj
     Return OBJ's property list.

set-object-properties!
 -- Scheme Procedure: set-object-properties! obj alist
     Set OBJ's property list to ALIST.

object-property
 -- Scheme Procedure: object-property obj key
     Return the property of OBJ with name KEY.

set-object-property!
 -- Scheme Procedure: set-object-property! obj key value
     In OBJ's property list, set the property named KEY to VALUE.

cons
 -- Scheme Procedure: cons x y
     Return a newly allocated pair whose car is X and whose cdr is Y.  The pair is guaranteed to be different (in the sense of eq?) from every previously existing object.

pair?
 -- Scheme Procedure: pair? x
     Return #t if X is a pair; otherwise return #f.

set-car!
 -- Scheme Procedure: set-car! pair value
     Stores VALUE in the car field of PAIR.  The value returned by set-car! is unspecified.

set-cdr!
 -- Scheme Procedure: set-cdr! pair value
     Stores VALUE in the cdr field of PAIR.  The value returned by set-cdr! is unspecified.

char-ready?
 -- Scheme Procedure: char-ready? [port]
     Return #t if a character is ready on input PORT and return #f otherwise.  If char-ready? returns #t then the next read-char operation on PORT is guaranteed not to hang.  If PORT is a file port at end of file then char-ready? returns #t. (char-ready? exists to make it possible for a program to accept characters from interactive ports without getting stuck waiting for input.  Any input editors associated with such ports must make sure that characters whose existence has been asserted by char-ready? cannot be rubbed out. If char-ready? were to return #f at end of file, a port at end of file would be indistinguishable from an interactive port that has no ready characters.)

drain-input
 -- Scheme Procedure: drain-input port
     This procedure clears a port's input buffers, similar to the way that force-output clears the output buffer.  The contents of the buffers are returned as a single string, e.g.,

          (define p (open-input-file ...))
          (drain-input p) => empty string, nothing buffered yet.
          (unread-char (read-char p) p)
          (drain-input p) => initial chars from p, up to the buffer size.

     Draining the buffers may be useful for cleanly finishing buffered I/O so that the file descriptor can be used directly for further input.

current-input-port
 -- Scheme Procedure: current-input-port
     Return the current input port.  This is the default port used by many input procedures.  Initially, current-input-port returns the standard input in Unix and C terminology.

current-output-port
 -- Scheme Procedure: current-output-port
     Return the current output port.  This is the default port used by many output procedures.  Initially, current-output-port returns the standard output in Unix and C terminology.

current-error-port
 -- Scheme Procedure: current-error-port
     Return the port to which errors and warnings should be sent (the standard error in Unix and C terminology).

current-load-port
 -- Scheme Procedure: current-load-port
     Return the current-load-port. The load port is used internally by primitive-load.

set-current-input-port
 -- Scheme Procedure: set-current-input-port port
 -- Scheme Procedure: set-current-output-port port
 -- Scheme Procedure: set-current-error-port port
     Change the ports returned by current-input-port, current-output-port and current-error-port, respectively, so that they use the supplied PORT for input or output.

set-current-output-port
 -- Scheme Procedure: set-current-output-port port
     Set the current default output port to PORT.

set-current-error-port
 -- Scheme Procedure: set-current-error-port port
     Set the current default error port to PORT.

port-revealed
 -- Scheme Procedure: port-revealed port
     Return the revealed count for PORT.

set-port-revealed!
 -- Scheme Procedure: set-port-revealed! port rcount
     Sets the revealed count for a port to a given value. The return value is unspecified.

port-mode
 -- Scheme Procedure: port-mode port
     Return the port modes associated with the open port PORT. These will not necessarily be identical to the modes used when the port was opened, since modes such as "append" which are used only during port creation are not retained.

close-port
 -- Scheme Procedure: close-port port
     Close the specified port object.  Return #t if it successfully closes a port or #f if it was already closed.  An exception may be raised if an error occurs, for example when flushing buffered output.  See also close, for a procedure which can close file descriptors.

close-input-port
 -- Scheme Procedure: close-input-port port
     Close the specified input port object.  The routine has no effect if the file has already been closed.  An exception may be raised if an error occurs.  The value returned is unspecified.

     See also close, for a procedure which can close file descriptors.

close-output-port
 -- Scheme Procedure: close-output-port port
     Close the specified output port object.  The routine has no effect if the file has already been closed.  An exception may be raised if an error occurs.  The value returned is unspecified.

     See also close, for a procedure which can close file descriptors.

port-for-each
 -- Scheme Procedure: port-for-each proc
     Apply PROC to each port in the Guile port table in turn.  The return value is unspecified.  More specifically, PROC is applied exactly once to every port that exists in the system at the time PORT-FOR-EACH is invoked. Changes to the port table while PORT-FOR-EACH is running have no effect as far as PORT-FOR-EACH is concerned.

close-all-ports-except
 -- Scheme Procedure: close-all-ports-except . ports
     [DEPRECATED] Close all open file ports used by the interpreter except for those supplied as arguments.  This procedure was intended to be used before an exec call to close file descriptors which are not needed in the new process.  However it has the undesirable side effect of flushing buffers, so it's deprecated. Use port-for-each instead.

input-port?
 -- Scheme Procedure: input-port? x
     Return #t if X is an input port, otherwise return #f.  Any object satisfying this predicate also satisfies port?.

output-port?
 -- Scheme Procedure: output-port? x
     Return #t if X is an output port, otherwise return #f.  Any object satisfying this predicate also satisfies port?.

port?
 -- Scheme Procedure: port? x
     Return a boolean indicating whether X is a port. Equivalent to (or (input-port? X) (output-port? X)).

port-closed?
 -- Scheme Procedure: port-closed? port
     Return #t if PORT is closed or #f if it is open.

eof-object?
 -- Scheme Procedure: eof-object? x
     Return #t if X is an end-of-file object; otherwise return #f.

force-output
 -- Scheme Procedure: force-output [port]
     Flush the specified output port, or the current output port if PORT is omitted.  The current output buffer contents are passed to the underlying port implementation (e.g., in the case of fports, the data will be written to the file and the output buffer will be cleared.) It has no effect on an unbuffered port.

     The return value is unspecified.

flush-all-ports
 -- Scheme Procedure: flush-all-ports
     Equivalent to calling force-output on all open output ports.  The return value is unspecified.

read-char
 -- Scheme Procedure: read-char [port]
     Return the next character available from PORT, updating PORT to point to the following character.  If no more characters are available, the end-of-file object is returned.

peek-char
 -- Scheme Procedure: peek-char [port]
     Return the next character available from PORT, without updating PORT to point to the following character.  If no more characters are available, the end-of-file object is returned. (The value returned by a call to peek-char is the same as the value that would have been returned by a call to read-char on the same port.  The only difference is that the very next call to read-char or peek-char on that PORT will return the value returned by the preceding call to peek-char.  In particular, a call to peek-char on an interactive port will hang waiting for input whenever a call to read-char would have hung.)

unread-char
 -- Scheme Procedure: unread-char cobj [port]
     Place CHAR in PORT so that it will be read by the next read operation.  If called multiple times, the unread characters will be read again in last-in first-out order.  If PORT is not supplied, the current input port is used.

unread-string
 -- Scheme Procedure: unread-string str port
     Place the string STR in PORT so that its characters will be read in subsequent read operations.  If called multiple times, the unread characters will be read again in last-in first-out order.  If PORT is not supplied, the current-input-port is used.

seek
 -- Scheme Procedure: seek fd_port offset whence
     Sets the current position of FD/PORT to the integer OFFSET, which is interpreted according to the value of WHENCE.

     One of the following variables should be supplied for WHENCE:
      -- Variable: SEEK_SET
          Seek from the beginning of the file.

      -- Variable: SEEK_CUR
          Seek from the current position.

      -- Variable: SEEK_END
          Seek from the end of the file.

     If FD/PORT is a file descriptor, the underlying system call is lseek.  PORT may be a string port.

     The value returned is the new position in the file.  This means that the current position of a port can be obtained using:

          (seek port 0 SEEK_CUR)

truncate-file
 -- Scheme Procedure: truncate-file object [length]
     Truncates the object referred to by OBJECT to at most LENGTH bytes.  OBJECT can be a string containing a file name or an integer file descriptor or a port. LENGTH may be omitted if OBJECT is not a file name, in which case the truncation occurs at the current port. position.  The return value is unspecified.

port-line
 -- Scheme Procedure: port-line port
     Return the current line number for PORT.

set-port-line!
 -- Scheme Procedure: set-port-line! port line
     Set the current line number for PORT to LINE.

port-column
 -- Scheme Procedure: port-column port
 -- Scheme Procedure: port-line port
     Return the current column number or line number of PORT, using the current input port if none is specified.  If the number is unknown, the result is #f.  Otherwise, the result is a 0-origin integer - i.e. the first character of the first line is line 0, column 0. (However, when you display a file position, for example in an error message, we recommend you add 1 to get 1-origin integers.  This is because lines and column numbers traditionally start with 1, and that is what non-programmers will find most natural.)

set-port-column!
 -- Scheme Procedure: set-port-column! port column
 -- Scheme Procedure: set-port-line! port line
     Set the current column or line number of PORT, using the current input port if none is specified.

port-filename
 -- Scheme Procedure: port-filename port
     Return the filename associated with PORT.  This function returns the strings "standard input", "standard output" and "standard error" when called on the current input, output and error ports respectively.

set-port-filename!
 -- Scheme Procedure: set-port-filename! port filename
     Change the filename associated with PORT, using the current input port if none is specified.  Note that this does not change the port's source of data, but only the value that is returned by port-filename and reported in diagnostic output.

%make-void-port
 -- Scheme Procedure: %make-void-port mode
     Create and return a new void port.  A void port acts like /dev/null.  The MODE argument specifies the input/output modes for this port: see the documentation for open-file in File Ports.

print-options-interface
 -- Scheme Procedure: print-options-interface [setting]
     Option interface for the print options. Instead of using this procedure directly, use the procedures print-enable, print-disable, print-set! and print-options.

simple-format
 -- Scheme Procedure: simple-format destination message . args
     Write MESSAGE to DESTINATION, defaulting to the current output port. MESSAGE can contain ~A (was %s) and ~S (was %S) escapes.  When printed, the escapes are replaced with corresponding members of ARGS: ~A formats using display and ~S formats using write. If DESTINATION is #t, then use the current output port, if DESTINATION is #f, then return a string containing the formatted text. Does not add a trailing newline.

newline
 -- Scheme Procedure: newline [port]
     Send a newline to PORT. If PORT is omitted, send to the current output port.

write-char
 -- Scheme Procedure: write-char chr [port]
     Send character CHR to PORT.

port-with-print-state
 -- Scheme Procedure: port-with-print-state port pstate
     Create a new port which behaves like PORT, but with an included print state PSTATE.

get-print-state
 -- Scheme Procedure: get-print-state port
     Return the print state of the port PORT. If PORT has no associated print state, #f is returned.

procedure-properties
 -- Scheme Procedure: procedure-properties proc
     Return OBJ's property list.

set-procedure-properties!
 -- Scheme Procedure: set-procedure-properties! proc new_val
     Set OBJ's property list to ALIST.

procedure-property
 -- Scheme Procedure: procedure-property p k
     Return the property of OBJ with name KEY.

set-procedure-property!
 -- Scheme Procedure: set-procedure-property! p k v
     In OBJ's property list, set the property named KEY to VALUE.

procedure?
 -- Scheme Procedure: procedure? obj
     Return #t if OBJ is a procedure.

closure?
 -- Scheme Procedure: closure? obj
     Return #t if OBJ is a closure.

thunk?
 -- Scheme Procedure: thunk? obj
     Return #t if OBJ is a thunk.

procedure-documentation
 -- Scheme Procedure: procedure-documentation proc
     Return the documentation string associated with proc.  By convention, if a procedure contains more than one expression and the first expression is a string constant, that string is assumed to contain documentation for that procedure.

procedure-with-setter?
 -- Scheme Procedure: procedure-with-setter? obj
     Return #t if OBJ is a procedure with an associated setter procedure.

make-procedure-with-setter
 -- Scheme Procedure: make-procedure-with-setter procedure setter
     Create a new procedure which behaves like PROCEDURE, but with the associated setter SETTER.

procedure
 -- Scheme Procedure: procedure proc
     Return the procedure of PROC, which must be either a procedure with setter, or an operator struct.

primitive-make-property
 -- Scheme Procedure: primitive-make-property not_found_proc
     Create a property token that can be used with primitive-property-ref and primitive-property-set!. See primitive-property-ref for the significance of NOT_FOUND_PROC.

primitive-property-ref
 -- Scheme Procedure: primitive-property-ref prop obj
     Return the property PROP of OBJ.  When no value has yet been associated with PROP and OBJ, call NOT-FOUND-PROC instead (see primitive-make-property) and use its return value.  That value is also associated with OBJ via primitive-property-set!.  When NOT-FOUND-PROC is #f, use #f as the default value of PROP.

primitive-property-set!
 -- Scheme Procedure: primitive-property-set! prop obj val
     Associate CODE with PROP and OBJ.

primitive-property-del!
 -- Scheme Procedure: primitive-property-del! prop obj
     Remove any value associated with PROP and OBJ.

random
 -- Scheme Procedure: random n [state]
     Return a number in [0,N).

     Accepts a positive integer or real n and returns a number of the same type between zero (inclusive) and N (exclusive). The values returned have a uniform distribution.

     The optional argument STATE must be of the type produced by seed->random-state. It defaults to the value of the variable *RANDOM-STATE*. This object is used to maintain the state of the pseudo-random-number generator and is altered as a side effect of the random operation.

copy-random-state
 -- Scheme Procedure: copy-random-state [state]
     Return a copy of the random state STATE.

seed->random-state
 -- Scheme Procedure: seed->random-state seed
     Return a new random state using SEED.

random:uniform
 -- Scheme Procedure: random:uniform [state]
     Return a uniformly distributed inexact real random number in [0,1).

random:normal
 -- Scheme Procedure: random:normal [state]
     Return an inexact real in a normal distribution.  The distribution used has mean 0 and standard deviation 1.  For a normal distribution with mean m and standard deviation d use (+ m (* d (random:normal))).

random:solid-sphere!
 -- Scheme Procedure: random:solid-sphere! v [state]
     Fills vect with inexact real random numbers the sum of whose squares is less than 1.0. Thinking of vect as coordinates in space of dimension n = (vector-length vect), the coordinates are uniformly distributed within the unit n-sphere. The sum of the squares of the numbers is returned.

random:hollow-sphere!
 -- Scheme Procedure: random:hollow-sphere! v [state]
     Fills vect with inexact real random numbers the sum of whose squares is equal to 1.0. Thinking of vect as coordinates in space of dimension n = (vector-length vect), the coordinates are uniformly distributed over the surface of the unit n-sphere.

random:normal-vector!
 -- Scheme Procedure: random:normal-vector! v [state]
     Fills vect with inexact real random numbers that are independent and standard normally distributed (i.e., with mean 0 and variance 1).

random:exp
 -- Scheme Procedure: random:exp [state]
     Return an inexact real in an exponential distribution with mean 1.  For an exponential distribution with mean u use (* u (random:exp)).

%read-delimited!
 -- Scheme Procedure: %read-delimited! delims str gobble [port [start [end]]]
     Read characters from PORT into STR until one of the characters in the DELIMS string is encountered.  If GOBBLE is true, discard the delimiter character; otherwise, leave it in the input stream for the next read.  If PORT is not specified, use the value of (current-input-port).  If START or END are specified, store data only into the substring of STR bounded by START and END (which default to the beginning and end of the string, respectively).

     Return a pair consisting of the delimiter that terminated the string and the number of characters read.  If reading stopped at the end of file, the delimiter returned is the EOF-OBJECT; if the string was filled without encountering a delimiter, this value is #f.

%read-line
 -- Scheme Procedure: %read-line [port]
     Read a newline-terminated line from PORT, allocating storage as necessary.  The newline terminator (if any) is removed from the string, and a pair consisting of the line and its delimiter is returned.  The delimiter may be either a newline or the EOF-OBJECT; if %read-line is called at the end of file, it returns the pair (#<eof> . #<eof>).

write-line
 -- Scheme Procedure: write-line obj [port]
     Display OBJ and a newline character to PORT.  If PORT is not specified, (current-output-port) is used.  This function is equivalent to:

          (display obj [port])
          (newline [port])

read-options-interface
 -- Scheme Procedure: read-options-interface [setting]
     Option interface for the read options. Instead of using this procedure directly, use the procedures read-enable, read-disable, read-set! and read-options.

read
 -- Scheme Procedure: read [port]
     Read an s-expression from the input port PORT, or from the current input port if PORT is not specified. Any whitespace before the next token is discarded.

read-hash-extend
 -- Scheme Procedure: read-hash-extend chr proc
     Install the procedure PROC for reading expressions starting with the character sequence # and CHR. PROC will be called with two arguments:  the character CHR and the port to read further data from. The object returned will be the return value of read.

call-with-dynamic-root
 -- Scheme Procedure: call-with-dynamic-root thunk handler
     Evaluate (thunk) in a new dynamic context, returning its value.

     If an error occurs during evaluation, apply HANDLER to the arguments to the throw, just as throw would.  If this happens, HANDLER is called outside the scope of the new root -- it is called in the same dynamic context in which call-with-dynamic-root was evaluated.

     If THUNK captures a continuation, the continuation is rooted at the call to THUNK.  In particular, the call to call-with-dynamic-root is not captured.  Therefore, call-with-dynamic-root always returns at most one time.

     Before calling THUNK, the dynamic-wind chain is un-wound back to the root and a new chain started for THUNK.  Therefore, this call may not do what you expect:

          ;; Almost certainly a bug:
          (with-output-to-port
           some-port

           (lambda ()
             (call-with-dynamic-root
              (lambda ()
                (display 'fnord)
                (newline))
              (lambda (errcode) errcode))))

     The problem is, on what port will fnord be displayed?  You might expect that because of the with-output-to-port that it will be displayed on the port bound to some-port.  But it probably won't -- before evaluating the thunk, dynamic winds are unwound, including those created by with-output-to-port. So, the standard output port will have been re-set to its default value before display is evaluated.

     (This function was added to Guile mostly to help calls to functions in C libraries that can not tolerate non-local exits or calls that return multiple times.  If such functions call back to the interpreter, it should be under a new dynamic root.)

dynamic-root
 -- Scheme Procedure: dynamic-root
     Return an object representing the current dynamic root.

     These objects are only useful for comparison using eq?. They are currently represented as numbers, but your code should in no way depend on this.

read-string!/partial
 -- Scheme Procedure: read-string!/partial str [port_or_fdes [start [end]]]
     Read characters from a port or file descriptor into a string STR.  A port must have an underlying file descriptor --- a so-called fport.  This procedure is scsh-compatible and can efficiently read large strings. It will:

       * attempt to fill the entire string, unless the START and/or END arguments are supplied.  i.e., START defaults to 0 and END defaults to (string-length str)

       * use the current input port if PORT_OR_FDES is not supplied.

       * return fewer than the requested number of characters in some cases, e.g., on end of file, if interrupted by a signal, or if not all the characters are immediately available.

       * wait indefinitely for some input if no characters are currently available, unless the port is in non-blocking mode.

       * read characters from the port's input buffers if available, instead from the underlying file descriptor.

       * return #f if end-of-file is encountered before reading any characters, otherwise return the number of characters read.

       * return 0 if the port is in non-blocking mode and no characters are immediately available.

       * return 0 if the request is for 0 bytes, with no end-of-file check.

write-string/partial
 -- Scheme Procedure: write-string/partial str [port_or_fdes [start [end]]]
     Write characters from a string STR to a port or file descriptor.  A port must have an underlying file descriptor --- a so-called fport.  This procedure is scsh-compatible and can efficiently write large strings. It will:

       * attempt to write the entire string, unless the START and/or END arguments are supplied.  i.e., START defaults to 0 and END defaults to (string-length str)

       * use the current output port if PORT_OF_FDES is not supplied.

       * in the case of a buffered port, store the characters in the port's output buffer, if all will fit.  If they will not fit then any existing buffered characters will be flushed before attempting to write the new characters directly to the underlying file descriptor.  If the port is in non-blocking mode and buffered characters can not be flushed immediately, then an EAGAIN system-error exception will be raised (Note: scsh does not support the use of non-blocking buffered ports.)

       * write fewer than the requested number of characters in some cases, e.g., if interrupted by a signal or if not all of the output can be accepted immediately.

       * wait indefinitely for at least one character from STR to be accepted by the port, unless the port is in non-blocking mode.

       * return the number of characters accepted by the port.

       * return 0 if the port is in non-blocking mode and can not accept at least one character from STR immediately

       * return 0 immediately if the request size is 0 bytes.

sigaction
 -- Scheme Procedure: sigaction signum [handler [flags]]
     Install or report the signal handler for a specified signal.

     SIGNUM is the signal number, which can be specified using the value of variables such as SIGINT.

     If ACTION is omitted, sigaction returns a pair: the CAR is the current signal hander, which will be either an integer with the value SIG_DFL (default action) or SIG_IGN (ignore), or the Scheme procedure which handles the signal, or #f if a non-Scheme procedure handles the signal.  The CDR contains the current sigaction flags for the handler.

     If ACTION is provided, it is installed as the new handler for SIGNUM.  ACTION can be a Scheme procedure taking one argument, or the value of SIG_DFL (default action) or SIG_IGN (ignore), or #f to restore whatever signal handler was installed before sigaction was first used.  Flags can optionally be specified for the new handler (SA_RESTART will always be added if it's available and the system is using restartable system calls.)  The return value is a pair with information about the old handler as described above.

     This interface does not provide access to the "signal blocking" facility.  Maybe this is not needed, since the thread support may provide solutions to the problem of consistent access to data structures.

restore-signals
 -- Scheme Procedure: restore-signals
     Return all signal handlers to the values they had before any call to sigaction was made.  The return value is unspecified.

alarm
 -- Scheme Procedure: alarm i
     Set a timer to raise a SIGALRM signal after the specified number of seconds (an integer).  It's advisable to install a signal handler for SIGALRM beforehand, since the default action is to terminate the process.

     The return value indicates the time remaining for the previous alarm, if any.  The new value replaces the previous alarm.  If there was no previous alarm, the return value is zero.

setitimer
 -- Scheme Procedure: setitimer which_timer interval_seconds interval_microseconds value_seconds value_microseconds
     Set the timer specified by WHICH_TIMER according to the given INTERVAL_SECONDS, INTERVAL_MICROSECONDS, VALUE_SECONDS, and VALUE_MICROSECONDS values.

     Return information about the timer's previous setting. Errors are handled as described in the guile info pages under ``POSIX Interface Conventions''.

     The timers available are: ITIMER_REAL, ITIMER_VIRTUAL, and ITIMER_PROF.

     The return value will be a list of two cons pairs representing the current state of the given timer.  The first pair is the seconds and microseconds of the timer it_interval, and the second pair is the seconds and microseconds of the timer it_value.

getitimer
 -- Scheme Procedure: getitimer which_timer
     Return information about the timer specified by WHICH_TIMER Errors are handled as described in the guile info pages under ``POSIX Interface Conventions''.

     The timers available are: ITIMER_REAL, ITIMER_VIRTUAL, and ITIMER_PROF.

     The return value will be a list of two cons pairs representing the current state of the given timer.  The first pair is the seconds and microseconds of the timer it_interval, and the second pair is the seconds and microseconds of the timer it_value.

pause
 -- Scheme Procedure: pause
     Pause the current process (thread?) until a signal arrives whose action is to either terminate the current process or invoke a handler procedure.  The return value is unspecified.

sleep
 -- Scheme Procedure: sleep i
     Wait for the given number of seconds (an integer) or until a signal arrives.  The return value is zero if the time elapses or the number of seconds remaining otherwise.

usleep
 -- Scheme Procedure: usleep i
     Sleep for I microseconds.  usleep is not available on all platforms.

raise
 -- Scheme Procedure: raise sig
     Sends a specified signal SIG to the current process, where SIG is as described for the kill procedure.

system
 -- Scheme Procedure: system [cmd]
     Execute CMD using the operating system's "command processor".  Under Unix this is usually the default shell sh.  The value returned is CMD's exit status as returned by waitpid, which can be interpreted using the functions above.

     If system is called without arguments, return a boolean indicating whether the command processor is available.

getenv
 -- Scheme Procedure: getenv nam
     Looks up the string NAME in the current environment.  The return value is #f unless a string of the form NAME=VALUE is found, in which case the string VALUE is returned.

primitive-exit
 -- Scheme Procedure: primitive-exit [status]
     Terminate the current process without unwinding the Scheme stack. This is would typically be useful after a fork.  The exit status is STATUS if supplied, otherwise zero.

restricted-vector-sort!
 -- Scheme Procedure: restricted-vector-sort! vec less startpos endpos
     Sort the vector VEC, using LESS for comparing the vector elements.  STARTPOS and ENDPOS delimit the range of the vector which gets sorted.  The return value is not specified.

sorted?
 -- Scheme Procedure: sorted? items less
     Return #t iff ITEMS is a list or a vector such that for all 1 <= i <= m, the predicate LESS returns true when applied to all elements i - 1 and i

merge
 -- Scheme Procedure: merge alist blist less
     Merge two already sorted lists into one. Given two lists ALIST and BLIST, such that (sorted? alist less?) and (sorted? blist less?), return a new list in which the elements of ALIST and BLIST have been stably interleaved so that (sorted? (merge alist blist less?) less?). Note:  this does _not_ accept vectors.

merge!
 -- Scheme Procedure: merge! alist blist less
     Takes two lists ALIST and BLIST such that (sorted? alist less?) and (sorted? blist less?) and returns a new list in which the elements of ALIST and BLIST have been stably interleaved so that (sorted? (merge alist blist less?) less?). This is the destructive variant of merge Note:  this does _not_ accept vectors.

sort!
 -- Scheme Procedure: sort! items less
     Sort the sequence ITEMS, which may be a list or a vector.  LESS is used for comparing the sequence elements.  The sorting is destructive, that means that the input sequence is modified to produce the sorted result. This is not a stable sort.

sort
 -- Scheme Procedure: sort items less
     Sort the sequence ITEMS, which may be a list or a vector.  LESS is used for comparing the sequence elements.  This is not a stable sort.

stable-sort!
 -- Scheme Procedure: stable-sort! items less
     Sort the sequence ITEMS, which may be a list or a vector. LESS is used for comparing the sequence elements. The sorting is destructive, that means that the input sequence is modified to produce the sorted result. This is a stable sort.

stable-sort
 -- Scheme Procedure: stable-sort items less
     Sort the sequence ITEMS, which may be a list or a vector. LESS is used for comparing the sequence elements. This is a stable sort.

sort-list!
 -- Scheme Procedure: sort-list! items less
     Sort the list ITEMS, using LESS for comparing the list elements. The sorting is destructive, that means that the input list is modified to produce the sorted result. This is a stable sort.

sort-list
 -- Scheme Procedure: sort-list items less
     Sort the list ITEMS, using LESS for comparing the list elements. This is a stable sort.

source-properties
 -- Scheme Procedure: source-properties obj
     Return the source property association list of OBJ.

set-source-properties!
 -- Scheme Procedure: set-source-properties! obj plist
     Install the association list PLIST as the source property list for OBJ.

source-property
 -- Scheme Procedure: source-property obj key
     Return the source property specified by KEY from OBJ's source property list.

set-source-property!
 -- Scheme Procedure: set-source-property! obj key datum
     Set the source property of object OBJ, which is specified by KEY to DATUM.  Normally, the key will be a symbol.

stack?
 -- Scheme Procedure: stack? obj
     Return #t if OBJ is a calling stack.

make-stack
 -- Scheme Procedure: make-stack obj . args
     Create a new stack. If OBJ is #t, the current evaluation stack is used for creating the stack frames, otherwise the frames are taken from OBJ (which must be either a debug object or a continuation).

     ARGS should be a list containing any combination of integer, procedure and #t values.

     These values specify various ways of cutting away uninteresting stack frames from the top and bottom of the stack that make-stack returns.  They come in pairs like this: (INNER_CUT_1 OUTER_CUT_1 INNER_CUT_2 OUTER_CUT_2 ...).

     Each INNER_CUT_N can be #t, an integer, or a procedure.  #t means to cut away all frames up to but excluding the first user module frame.  An integer means to cut away exactly that number of frames.  A procedure means to cut away all frames up to but excluding the application frame whose procedure matches the specified one.

     Each OUTER_CUT_N can be an integer or a procedure.  An integer means to cut away that number of frames.  A procedure means to cut away frames down to but excluding the application frame whose procedure matches the specified one.

     If the OUTER_CUT_N of the last pair is missing, it is taken as 0.

stack-id
 -- Scheme Procedure: stack-id stack
     Return the identifier given to STACK by start-stack.

stack-ref
 -- Scheme Procedure: stack-ref stack index
     Return the INDEX'th frame from STACK.

stack-length
 -- Scheme Procedure: stack-length stack
     Return the length of STACK.

frame?
 -- Scheme Procedure: frame? obj
     Return #t if OBJ is a stack frame.

last-stack-frame
 -- Scheme Procedure: last-stack-frame obj
     Return a stack which consists of a single frame, which is the last stack frame for OBJ. OBJ must be either a debug object or a continuation.

frame-number
 -- Scheme Procedure: frame-number frame
     Return the frame number of FRAME.

frame-source
 -- Scheme Procedure: frame-source frame
     Return the source of FRAME.

frame-procedure
 -- Scheme Procedure: frame-procedure frame
     Return the procedure for FRAME, or #f if no procedure is associated with FRAME.

frame-arguments
 -- Scheme Procedure: frame-arguments frame
     Return the arguments of FRAME.

frame-previous
 -- Scheme Procedure: frame-previous frame
     Return the previous frame of FRAME, or #f if FRAME is the first frame in its stack.

frame-next
 -- Scheme Procedure: frame-next frame
     Return the next frame of FRAME, or #f if FRAME is the last frame in its stack.

frame-real?
 -- Scheme Procedure: frame-real? frame
     Return #t if FRAME is a real frame.

frame-procedure?
 -- Scheme Procedure: frame-procedure? frame
     Return #t if a procedure is associated with FRAME.

frame-evaluating-args?
 -- Scheme Procedure: frame-evaluating-args? frame
     Return #t if FRAME contains evaluated arguments.

frame-overflow?
 -- Scheme Procedure: frame-overflow? frame
     Return #t if FRAME is an overflow frame.

get-internal-real-time
 -- Scheme Procedure: get-internal-real-time
     Return the number of time units since the interpreter was started.

times
 -- Scheme Procedure: times
     Return an object with information about real and processor time.  The following procedures accept such an object as an argument and return a selected component:

     tms:clock
          The current real time, expressed as time units relative to an arbitrary base.

     tms:utime
          The CPU time units used by the calling process.

     tms:stime
          The CPU time units used by the system on behalf of the calling process.

     tms:cutime
          The CPU time units used by terminated child processes of the calling process, whose status has been collected (e.g., using waitpid).

     tms:cstime
          Similarly, the CPU times units used by the system on behalf of terminated child processes.

get-internal-run-time
 -- Scheme Procedure: get-internal-run-time
     Return the number of time units of processor time used by the interpreter.  Both system and user time are included but subprocesses are not.

current-time
 -- Scheme Procedure: current-time
     Return the number of seconds since 1970-01-01 00:00:00 UTC, excluding leap seconds.

gettimeofday
 -- Scheme Procedure: gettimeofday
     Return a pair containing the number of seconds and microseconds since 1970-01-01 00:00:00 UTC, excluding leap seconds.  Note: whether true microsecond resolution is available depends on the operating system.

localtime
 -- Scheme Procedure: localtime time [zone]
     Return an object representing the broken down components of TIME, an integer like the one returned by current-time.  The time zone for the calculation is optionally specified by ZONE (a string), otherwise the TZ environment variable or the system default is used.

gmtime
 -- Scheme Procedure: gmtime time
     Return an object representing the broken down components of TIME, an integer like the one returned by current-time.  The values are calculated for UTC.

mktime
 -- Scheme Procedure: mktime sbd_time [zone]
     BD-TIME is an object representing broken down time and zone is an optional time zone specifier (otherwise the TZ environment variable or the system default is used).

     Returns a pair: the car is a corresponding integer time value like that returned by current-time; the cdr is a broken down time object, similar to as BD-TIME but with normalized values.

tzset
 -- Scheme Procedure: tzset
     Initialize the timezone from the TZ environment variable or the system default.  It's not usually necessary to call this procedure since it's done automatically by other procedures that depend on the timezone.

strftime
 -- Scheme Procedure: strftime format stime
     Formats a time specification TIME using TEMPLATE.  TIME is an object with time components in the form returned by localtime or gmtime.  TEMPLATE is a string which can include formatting specifications introduced by a % character.  The formatting of month and day names is dependent on the current locale.  The value returned is the formatted string. See Formatting Date and Time (The GNU C Library Reference Manual).)

strptime
 -- Scheme Procedure: strptime format string
     Performs the reverse action to strftime, parsing STRING according to the specification supplied in TEMPLATE.  The interpretation of month and day names is dependent on the current locale.  The value returned is a pair. The car has an object with time components in the form returned by localtime or gmtime, but the time zone components are not usefully set. The cdr reports the number of characters from STRING which were used for the conversion.

string?
 -- Scheme Procedure: string? obj
     Return #t if OBJ is a string, else #f.

read-only-string?
 -- Scheme Procedure: read-only-string? obj
     Return #t if OBJ is either a string or a symbol, otherwise return #f.

list->string
 -- Scheme Procedure: list->string
     implemented by the C function "scm_string"

string
 -- Scheme Procedure: string . chrs
 -- Scheme Procedure: list->string chrs
     Return a newly allocated string composed of the arguments, CHRS.

make-string
 -- Scheme Procedure: make-string k [chr]
     Return a newly allocated string of length K.  If CHR is given, then all elements of the string are initialized to CHR, otherwise the contents of the STRING are unspecified.

string-length
 -- Scheme Procedure: string-length string
     Return the number of characters in STRING.

string-ref
 -- Scheme Procedure: string-ref str k
     Return character K of STR using zero-origin indexing. K must be a valid index of STR.

string-set!
 -- Scheme Procedure: string-set! str k chr
     Store CHR in element K of STR and return an unspecified value. K must be a valid index of STR.

substring
 -- Scheme Procedure: substring str start [end]
     Return a newly allocated string formed from the characters of STR beginning with index START (inclusive) and ending with index END (exclusive). STR must be a string, START and END must be exact integers satisfying:

     0 <= START <= END <= (string-length STR).

string-append
 -- Scheme Procedure: string-append . args
     Return a newly allocated string whose characters form the concatenation of the given strings, ARGS.

make-shared-substring
 -- Scheme Procedure: make-shared-substring str [start [end]]
     Return a shared substring of STR.  The arguments are the same as for the substring function: the shared substring returned includes all of the text from STR between indexes START (inclusive) and END (exclusive).  If END is omitted, it defaults to the end of STR.  The shared substring returned by make-shared-substring occupies the same storage space as STR.

string-index
 -- Scheme Procedure: string-index str chr [frm [to]]
     Return the index of the first occurrence of CHR in STR.  The optional integer arguments FRM and TO limit the search to a portion of the string.  This procedure essentially implements the index or strchr functions from the C library.

          (string-index "weiner" #\e)
          => 1

          (string-index "weiner" #\e 2)
          => 4

          (string-index "weiner" #\e 2 4)
          => #f

string-rindex
 -- Scheme Procedure: string-rindex str chr [frm [to]]
     Like string-index, but search from the right of the string rather than from the left.  This procedure essentially implements the rindex or strrchr functions from the C library.

          (string-rindex "weiner" #\e)
          => 4

          (string-rindex "weiner" #\e 2 4)
          => #f

          (string-rindex "weiner" #\e 2 5)
          => 4

substring-move-left!
 -- Scheme Procedure: substring-move-left!
     implemented by the C function "scm_substring_move_x"

substring-move-right!
 -- Scheme Procedure: substring-move-right!
     implemented by the C function "scm_substring_move_x"

substring-move!
 -- Scheme Procedure: substring-move! str1 start1 end1 str2 start2
     Copy the substring of STR1 bounded by START1 and END1 into STR2 beginning at position START2. STR1 and STR2 can be the same string.

substring-fill!
 -- Scheme Procedure: substring-fill! str start end fill
     Change every character in STR between START and END to FILL.

          (define y "abcdefg")
          (substring-fill! y 1 3 #\r)
          y
          => "arrdefg"

string-null?
 -- Scheme Procedure: string-null? str
     Return #t if STR's length is zero, and #f otherwise.

          (string-null? "")  => #t
          y                    => "foo"
          (string-null? y)     => #f

string->list
 -- Scheme Procedure: string->list str
     Return a newly allocated list of the characters that make up the given string STR. string->list and list->string are inverses as far as equal? is concerned.

string-copy
 -- Scheme Procedure: string-copy str
     Return a newly allocated copy of the given STRING.

string-fill!
 -- Scheme Procedure: string-fill! str chr
     Store CHAR in every element of the given STRING and return an unspecified value.

string-upcase!
 -- Scheme Procedure: string-upcase! str
     Destructively upcase every character in STR and return STR.

          y                  => "arrdefg"
          (string-upcase! y) => "ARRDEFG"
          y                  => "ARRDEFG"

string-upcase
 -- Scheme Procedure: string-upcase str
     Return a freshly allocated string containing the characters of STR in upper case.

string-downcase!
 -- Scheme Procedure: string-downcase! str
     Destructively downcase every character in STR and return STR.

          y                     => "ARRDEFG"
          (string-downcase! y)  => "arrdefg"
          y                     => "arrdefg"

string-downcase
 -- Scheme Procedure: string-downcase str
     Return a freshly allocation string containing the characters in STR in lower case.

string-capitalize!
 -- Scheme Procedure: string-capitalize! str
     Upcase the first character of every word in STR destructively and return STR.

          y                      => "hello world"
          (string-capitalize! y) => "Hello World"
          y                      => "Hello World"

string-capitalize
 -- Scheme Procedure: string-capitalize str
     Return a freshly allocated string with the characters in STR, where the first character of every word is capitalized.

string-split
 -- Scheme Procedure: string-split str chr
     Split the string STR into the a list of the substrings delimited by appearances of the character CHR.  Note that an empty substring between separator characters will result in an empty string in the result list.

          (string-split "root:x:0:0:root:/root:/bin/bash" #\:)
          =>
          ("root" "x" "0" "0" "root" "/root" "/bin/bash")

          (string-split "::" #\:)
          =>
          ("" "" "")

          (string-split "" #\:)
          =>
          ("")

string-ci->symbol
 -- Scheme Procedure: string-ci->symbol str
     Return the symbol whose name is STR.  STR is converted to lowercase before the conversion is done, if Guile is currently reading symbols case-insensitively.

string=?
 -- Scheme Procedure: string=? s1 s2
     Lexicographic equality predicate; return #t if the two strings are the same length and contain the same characters in the same positions, otherwise return #f.

     The procedure string-ci=? treats upper and lower case letters as though they were the same character, but string=? treats upper and lower case as distinct characters.

string-ci=?
 -- Scheme Procedure: string-ci=? s1 s2
     Case-insensitive string equality predicate; return #t if the two strings are the same length and their component characters match (ignoring case) at each position; otherwise return #f.

string<?
 -- Scheme Procedure: string<? s1 s2
     Lexicographic ordering predicate; return #t if S1 is lexicographically less than S2.

string<=?
 -- Scheme Procedure: string<=? s1 s2
     Lexicographic ordering predicate; return #t if S1 is lexicographically less than or equal to S2.

string>?
 -- Scheme Procedure: string>? s1 s2
     Lexicographic ordering predicate; return #t if S1 is lexicographically greater than S2.

string>=?
 -- Scheme Procedure: string>=? s1 s2
     Lexicographic ordering predicate; return #t if S1 is lexicographically greater than or equal to S2.

string-ci<?
 -- Scheme Procedure: string-ci<? s1 s2
     Case insensitive lexicographic ordering predicate; return #t if S1 is lexicographically less than S2 regardless of case.

string-ci<=?
 -- Scheme Procedure: string-ci<=? s1 s2
     Case insensitive lexicographic ordering predicate; return #t if S1 is lexicographically less than or equal to S2 regardless of case.

string-ci>?
 -- Scheme Procedure: string-ci>? s1 s2
     Case insensitive lexicographic ordering predicate; return #t if S1 is lexicographically greater than S2 regardless of case.

string-ci>=?
 -- Scheme Procedure: string-ci>=? s1 s2
     Case insensitive lexicographic ordering predicate; return #t if S1 is lexicographically greater than or equal to S2 regardless of case.

object->string
 -- Scheme Procedure: object->string obj [printer]
     Return a Scheme string obtained by printing OBJ. Printing function can be specified by the optional second argument PRINTER (default: write).

call-with-output-string
 -- Scheme Procedure: call-with-output-string proc
     Calls the one-argument procedure PROC with a newly created output port.  When the function returns, the string composed of the characters written into the port is returned.

call-with-input-string
 -- Scheme Procedure: call-with-input-string string proc
     Calls the one-argument procedure PROC with a newly created input port from which STRING's contents may be read.  The value yielded by the PROC is returned.

open-input-string
 -- Scheme Procedure: open-input-string str
     Take a string and return an input port that delivers characters from the string. The port can be closed by close-input-port, though its storage will be reclaimed by the garbage collector if it becomes inaccessible.

open-output-string
 -- Scheme Procedure: open-output-string
     Return an output port that will accumulate characters for retrieval by get-output-string. The port can be closed by the procedure close-output-port, though its storage will be reclaimed by the garbage collector if it becomes inaccessible.

get-output-string
 -- Scheme Procedure: get-output-string port
     Given an output port created by open-output-string, return a string consisting of the characters that have been output to the port so far.

eval-string
 -- Scheme Procedure: eval-string string
     Evaluate STRING as the text representation of a Scheme form or forms, and return whatever value they produce. Evaluation takes place in the environment returned by the procedure interaction-environment.

make-struct-layout
 -- Scheme Procedure: make-struct-layout fields
     Return a new structure layout object.

     FIELDS must be a string made up of pairs of characters strung together.  The first character of each pair describes a field type, the second a field protection.  Allowed types are 'p' for GC-protected Scheme data, 'u' for unprotected binary data, and 's' for a field that points to the structure itself.    Allowed protections are 'w' for mutable fields, 'r' for read-only fields, and 'o' for opaque fields.  The last field protection specification may be capitalized to indicate that the field is a tail-array.

struct?
 -- Scheme Procedure: struct? x
     Return #t iff X is a structure object, else #f.

struct-vtable?
 -- Scheme Procedure: struct-vtable? x
     Return #t iff X is a vtable structure.

make-struct
 -- Scheme Procedure: make-struct vtable tail_array_size . init
     Create a new structure.

     TYPE must be a vtable structure (see Vtables).

     TAIL-ELTS must be a non-negative integer.  If the layout specification indicated by TYPE includes a tail-array, this is the number of elements allocated to that array.

     The INIT1, ... are optional arguments describing how successive fields of the structure should be initialized.  Only fields with protection 'r' or 'w' can be initialized, except for fields of type 's', which are automatically initialized to point to the new structure itself; fields with protection 'o' can not be initialized by Scheme programs.

     If fewer optional arguments than initializable fields are supplied, fields of type 'p' get default value #f while fields of type 'u' are initialized to 0.

     Structs are currently the basic representation for record-like data structures in Guile.  The plan is to eventually replace them with a new representation which will at the same time be easier to use and more powerful.

     For more information, see the documentation for make-vtable-vtable.

make-vtable-vtable
 -- Scheme Procedure: make-vtable-vtable user_fields tail_array_size . init
     Return a new, self-describing vtable structure.

     USER-FIELDS is a string describing user defined fields of the vtable beginning at index vtable-offset-user (see make-struct-layout).

     TAIL-SIZE specifies the size of the tail-array (if any) of this vtable.

     INIT1, ... are the optional initializers for the fields of the vtable.

     Vtables have one initializable system field---the struct printer. This field comes before the user fields in the initializers passed to make-vtable-vtable and make-struct, and thus works as a third optional argument to make-vtable-vtable and a fourth to make-struct when creating vtables:

     If the value is a procedure, it will be called instead of the standard printer whenever a struct described by this vtable is printed. The procedure will be called with arguments STRUCT and PORT.

     The structure of a struct is described by a vtable, so the vtable is in essence the type of the struct.  The vtable is itself a struct with a vtable.  This could go on forever if it weren't for the vtable-vtables which are self-describing vtables, and thus terminate the chain.

     There are several potential ways of using structs, but the standard one is to use three kinds of structs, together building up a type sub-system: one vtable-vtable working as the root and one or several "types", each with a set of "instances".  (The vtable-vtable should be compared to the class <class> which is the class of itself.)

          (define ball-root (make-vtable-vtable "pr" 0))

          (define (make-ball-type ball-color)
            (make-struct ball-root 0
          	       (make-struct-layout "pw")
                         (lambda (ball port)
                           (format port "#<a ~A ball owned by ~A>"
                                   (color ball)
                                   (owner ball)))
                         ball-color))
          (define (color ball) (struct-ref (struct-vtable ball) vtable-offset-user))
          (define (owner ball) (struct-ref ball 0))

          (define red (make-ball-type 'red))
          (define green (make-ball-type 'green))

          (define (make-ball type owner) (make-struct type 0 owner))

          (define ball (make-ball green 'Nisse))
          ball => #<a green ball owned by Nisse>

struct-ref
 -- Scheme Procedure: struct-ref handle pos
 -- Scheme Procedure: struct-set! struct n value
     Access (or modify) the Nth field of STRUCT.

     If the field is of type 'p', then it can be set to an arbitrary value.

     If the field is of type 'u', then it can only be set to a non-negative integer value small enough to fit in one machine word.

struct-set!
 -- Scheme Procedure: struct-set! handle pos val
     Set the slot of the structure HANDLE with index POS to VAL.  Signal an error if the slot can not be written to.

struct-vtable
 -- Scheme Procedure: struct-vtable handle
     Return the vtable structure that describes the type of STRUCT.

struct-vtable-tag
 -- Scheme Procedure: struct-vtable-tag handle
     Return the vtable tag of the structure HANDLE.

struct-vtable-name
 -- Scheme Procedure: struct-vtable-name vtable
     Return the name of the vtable VTABLE.

set-struct-vtable-name!
 -- Scheme Procedure: set-struct-vtable-name! vtable name
     Set the name of the vtable VTABLE to NAME.

symbol?
 -- Scheme Procedure: symbol? obj
     Return #t if OBJ is a symbol, otherwise return #f.

symbol->string
 -- Scheme Procedure: symbol->string s
     Return the name of SYMBOL as a string.  If the symbol was part of an object returned as the value of a literal expression (section see Literal expressions (The Revised^5 Report on Scheme)) or by a call to the read procedure, and its name contains alphabetic characters, then the string returned will contain characters in the implementation's preferred standard case---some implementations will prefer upper case, others lower case.  If the symbol was returned by string->symbol, the case of characters in the string returned will be the same as the case in the string that was passed to string->symbol.  It is an error to apply mutation procedures like string-set! to strings returned by this procedure.

     The following examples assume that the implementation's standard case is lower case:

          (symbol->string 'flying-fish)    => "flying-fish"
          (symbol->string 'Martin)         =>  "martin"
          (symbol->string
             (string->symbol "Malvina")) => "Malvina"

string->symbol
 -- Scheme Procedure: string->symbol string
     Return the symbol whose name is STRING. This procedure can create symbols with names containing special characters or letters in the non-standard case, but it is usually a bad idea to create such symbols because in some implementations of Scheme they cannot be read as themselves.  See symbol->string.

     The following examples assume that the implementation's standard case is lower case:

          (eq? 'mISSISSIppi 'mississippi) => #t
          (string->symbol "mISSISSIppi") => the symbol with name "mISSISSIppi"
          (eq? 'bitBlt (string->symbol "bitBlt")) => #f
          (eq? 'JollyWog
            (string->symbol (symbol->string 'JollyWog))) => #t
          (string=? "K. Harper, M.D."
            (symbol->string
              (string->symbol "K. Harper, M.D."))) =>#t

gensym
 -- Scheme Procedure: gensym [prefix]
     Create a new symbol with a name constructed from a prefix and a counter value. The string PREFIX can be specified as an optional argument. Default prefix is  g.  The counter is increased by 1 at each call. There is no provision for resetting the counter.

symbol-hash
 -- Scheme Procedure: symbol-hash symbol
     Return a hash value for SYMBOL.

symbol-fref
 -- Scheme Procedure: symbol-fref s
     Return the contents of SYMBOL's function slot.

symbol-pref
 -- Scheme Procedure: symbol-pref s
     Return the property list currently associated with SYMBOL.

symbol-fset!
 -- Scheme Procedure: symbol-fset! s val
     Change the binding of SYMBOL's function slot.

symbol-pset!
 -- Scheme Procedure: symbol-pset! s val
     Change the binding of SYMBOL's property slot.

catch
 -- Scheme Procedure: catch key thunk handler
     Invoke THUNK in the dynamic context of HANDLER for exceptions matching KEY.  If thunk throws to the symbol KEY, then HANDLER is invoked this way:

          (handler key args ...)

     KEY is a symbol or #t.

     THUNK takes no arguments.  If THUNK returns normally, that is the return value of catch.

     Handler is invoked outside the scope of its own catch. If HANDLER again throws to the same key, a new handler from further up the call chain is invoked.

     If the key is #t, then a throw to any symbol will match this call to catch.

lazy-catch
 -- Scheme Procedure: lazy-catch key thunk handler
     This behaves exactly like catch, except that it does not unwind the stack before invoking HANDLER. The HANDLER procedure is not allowed to return: it must throw to another catch, or otherwise exit non-locally.

throw
 -- Scheme Procedure: throw key . args
     Invoke the catch form matching KEY, passing ARGS to the HANDLER.

     KEY is a symbol.  It will match catches of the same symbol or of #t.

     If there is no handler at all, Guile prints an error and then exits.

values
 -- Scheme Procedure: values . args
     Delivers all of its arguments to its continuation.  Except for continuations created by the call-with-values procedure, all continuations take exactly one value.  The effect of passing no value or more than one value to continuations that were not created by call-with-values is unspecified.

make-variable
 -- Scheme Procedure: make-variable init
     Return a variable initialized to value INIT.

make-undefined-variable
 -- Scheme Procedure: make-undefined-variable
     Return a variable that is initially unbound.

variable?
 -- Scheme Procedure: variable? obj
     Return #t iff OBJ is a variable object, else return #f.

variable-ref
 -- Scheme Procedure: variable-ref var
     Dereference VAR and return its value. VAR must be a variable object; see make-variable and make-undefined-variable.

variable-set!
 -- Scheme Procedure: variable-set! var val
     Set the value of the variable VAR to VAL. VAR must be a variable object, VAL can be any value. Return an unspecified value.

variable-bound?
 -- Scheme Procedure: variable-bound? var
     Return #t iff VAR is bound to a value. Throws an error if VAR is not a variable object.

variable-set-name-hint!
 -- Scheme Procedure: variable-set-name-hint! var hint
     Do not use this function.

builtin-variable
 -- Scheme Procedure: builtin-variable name
     Return the built-in variable with the name NAME. NAME must be a symbol (not a string). Then use variable-ref to access its value.

vector?
 -- Scheme Procedure: vector? obj
     Return #t if OBJ is a vector, otherwise return #f.

list->vector
 -- Scheme Procedure: list->vector
     implemented by the C function "scm_vector"

vector
 -- Scheme Procedure: vector . l
 -- Scheme Procedure: list->vector l
     Return a newly allocated vector whose elements contain the given arguments.  Analogous to list.

          (vector 'a 'b 'c) => #(a b c)

make-vector
 -- Scheme Procedure: make-vector k [fill]
     Return a newly allocated vector of K elements.  If a second argument is given, then each element is initialized to FILL.  Otherwise the initial contents of each element is unspecified.

vector->list
 -- Scheme Procedure: vector->list v
     Return a newly allocated list of the objects contained in the elements of VECTOR.

          (vector->list '#(dah dah didah)) =>  (dah dah didah)
          (list->vector '(dididit dah)) =>  #(dididit dah)

vector-fill!
 -- Scheme Procedure: vector-fill! v fill
     Store FILL in every element of VECTOR.  The value returned by vector-fill! is unspecified.

vector-move-left!
 -- Scheme Procedure: vector-move-left! vec1 start1 end1 vec2 start2
     Copy elements from VEC1, positions START1 to END1, to VEC2 starting at position START2.  START1 and START2 are inclusive indices; END1 is exclusive.

     vector-move-left! copies elements in leftmost order. Therefore, in the case where VEC1 and VEC2 refer to the same vector, vector-move-left! is usually appropriate when START1 is greater than START2.

vector-move-right!
 -- Scheme Procedure: vector-move-right! vec1 start1 end1 vec2 start2
     Copy elements from VEC1, positions START1 to END1, to VEC2 starting at position START2.  START1 and START2 are inclusive indices; END1 is exclusive.

     vector-move-right! copies elements in rightmost order. Therefore, in the case where VEC1 and VEC2 refer to the same vector, vector-move-right! is usually appropriate when START1 is less than START2.

major-version
 -- Scheme Procedure: major-version
     Return a string containing Guile's major version number. E.g., the 1 in "1.6.5".

minor-version
 -- Scheme Procedure: minor-version
     Return a string containing Guile's minor version number. E.g., the 6 in "1.6.5".

micro-version
 -- Scheme Procedure: micro-version
     Return a string containing Guile's micro version number. E.g., the 5 in "1.6.5".

version
 -- Scheme Procedure: version
 -- Scheme Procedure: major-version
 -- Scheme Procedure: minor-version
 -- Scheme Procedure: micro-version
     Return a string describing Guile's version number, or its major, minor or micro version number, respectively.

          (version) => "1.6.0"
          (major-version) => "1"
          (minor-version) => "6"
          (micro-version) => "0"

effective-version
 -- Scheme Procedure: effective-version
     Return a string describing Guile's effective version number.

          (version) => "1.6.0"
          (effective-version) => "1.6"
          (major-version) => "1"
          (minor-version) => "6"
          (micro-version) => "0"

make-soft-port
 -- Scheme Procedure: make-soft-port pv modes
     Return a port capable of receiving or delivering characters as specified by the MODES string (see open-file).  PV must be a vector of length 5.  Its components are as follows:

      0. procedure accepting one character for output

      1. procedure accepting a string for output

      2. thunk for flushing output

      3. thunk for getting one character

      4. thunk for closing port (not by garbage collection)

     For an output-only port only elements 0, 1, 2, and 4 need be procedures.  For an input-only port only elements 3 and 4 need be procedures.  Thunks 2 and 4 can instead be #f if there is no useful operation for them to perform.

     If thunk 3 returns #f or an eof-object (see eof-object? (The Revised^5 Report on Scheme)) it indicates that the port has reached end-of-file. For example:

          (define stdout (current-output-port))
          (define p (make-soft-port
                     (vector
                      (lambda (c) (write c stdout))
                      (lambda (s) (display s stdout))
                      (lambda () (display "." stdout))
                      (lambda () (char-upcase (read-char)))
                      (lambda () (display "@" stdout)))
                     "rw"))

          (write p p) => #<input-output: soft 8081e20>

make-weak-vector
 -- Scheme Procedure: make-weak-vector size [fill]
     Return a weak vector with SIZE elements. If the optional argument FILL is given, all entries in the vector will be set to FILL. The default value for FILL is the empty list.

list->weak-vector
 -- Scheme Procedure: list->weak-vector
     implemented by the C function "scm_weak_vector"

weak-vector
 -- Scheme Procedure: weak-vector . l
 -- Scheme Procedure: list->weak-vector l
     Construct a weak vector from a list: weak-vector uses the list of its arguments while list->weak-vector uses its only argument L (a list) to construct a weak vector the same way list->vector would.

weak-vector?
 -- Scheme Procedure: weak-vector? obj
     Return #t if OBJ is a weak vector. Note that all weak hashes are also weak vectors.

make-weak-key-hash-table
 -- Scheme Procedure: make-weak-key-hash-table size
 -- Scheme Procedure: make-weak-value-hash-table size
 -- Scheme Procedure: make-doubly-weak-hash-table size
     Return a weak hash table with SIZE buckets. As with any hash table, choosing a good size for the table requires some caution.

     You can modify weak hash tables in exactly the same way you would modify regular hash tables. (see Hash Tables)

make-weak-value-hash-table
 -- Scheme Procedure: make-weak-value-hash-table size
     Return a hash table with weak values with SIZE buckets. (see Hash Tables)

make-doubly-weak-hash-table
 -- Scheme Procedure: make-doubly-weak-hash-table size
     Return a hash table with weak keys and values with SIZE buckets.  (see Hash Tables)

weak-key-hash-table?
 -- Scheme Procedure: weak-key-hash-table? obj
 -- Scheme Procedure: weak-value-hash-table? obj
 -- Scheme Procedure: doubly-weak-hash-table? obj
     Return #t if OBJ is the specified weak hash table. Note that a doubly weak hash table is neither a weak key nor a weak value hash table.

weak-value-hash-table?
 -- Scheme Procedure: weak-value-hash-table? obj
     Return #t if OBJ is a weak value hash table.

doubly-weak-hash-table?
 -- Scheme Procedure: doubly-weak-hash-table? obj
     Return #t if OBJ is a doubly weak hash table.

string->obarray-symbol
 -- Scheme Procedure: string->obarray-symbol o s [softp]
     Intern a new symbol in OBARRAY, a symbol table, with name STRING.

     If OBARRAY is #f, use the default system symbol table.  If OBARRAY is #t, the symbol should not be interned in any symbol table; merely return the pair (SYMBOL . #<UNDEFINED>).

     The SOFT? argument determines whether new symbol table entries should be created when the specified symbol is not already present in OBARRAY.  If SOFT? is specified and is a true value, then new entries should not be added for symbols not already present in the table; instead, simply return #f.

intern-symbol
 -- Scheme Procedure: intern-symbol o s
     Add a new symbol to OBARRAY with name STRING, bound to an unspecified initial value.  The symbol table is not modified if a symbol with this name is already present.

unintern-symbol
 -- Scheme Procedure: unintern-symbol o s
     Remove the symbol with name STRING from OBARRAY.  This function returns #t if the symbol was present and #f otherwise.

symbol-binding
 -- Scheme Procedure: symbol-binding o s
     Look up in OBARRAY the symbol whose name is STRING, and return the value to which it is bound.  If OBARRAY is #f, use the global symbol table.  If STRING is not interned in OBARRAY, an error is signalled.

symbol-interned?
 -- Scheme Procedure: symbol-interned? o s
     Return #t if OBARRAY contains a symbol with name STRING, and #f otherwise.

symbol-bound?
 -- Scheme Procedure: symbol-bound? o s
     Return #t if OBARRAY contains a symbol with name STRING bound to a defined value.  This differs from SYMBOL-INTERNED? in that the mere mention of a symbol usually causes it to be interned; symbol-bound? determines whether a symbol has been given any meaningful value.

symbol-set!
 -- Scheme Procedure: symbol-set! o s v
     Find the symbol in OBARRAY whose name is STRING, and rebind it to VALUE.  An error is signalled if STRING is not present in OBARRAY.

gentemp
 -- Scheme Procedure: gentemp [prefix [obarray]]
     Create a new symbol with a name unique in an obarray. The name is constructed from an optional string PREFIX and a counter value.  The default prefix is t.  The OBARRAY is specified as a second optional argument. Default is the system obarray where all normal symbols are interned.  The counter is increased by 1 at each call.  There is no provision for resetting the counter.

array-fill!
 -- Scheme Procedure: array-fill! ra fill
     Store FILL in every element of ARRAY.  The value returned is unspecified.

array-copy-in-order!
 -- Scheme Procedure: array-copy-in-order!
     implemented by the C function "scm_array_copy_x"

array-copy!
 -- Scheme Procedure: array-copy! src dst
 -- Scheme Procedure: array-copy-in-order! src dst
     Copy every element from vector or array SOURCE to the corresponding element of DESTINATION.  DESTINATION must have the same rank as SOURCE, and be at least as large in each dimension.  The order is unspecified.

array-map-in-order!
 -- Scheme Procedure: array-map-in-order!
     implemented by the C function "scm_array_map_x"

array-map!
 -- Scheme Procedure: array-map! dest proc . sources
     DEST must be an array, and SOURCES must be a non-empty list of arrays where each element must have the same number of dimensions as DEST and must have a range for each index which includes the range for the corresponding index in DEST.  PROC is applied to each tuple of elements of SOURCES and the result is stored as the corresponding element in DEST.  The value returned is unspecified, and the order of application is unspecified.

array-for-each
 -- Scheme Procedure: array-for-each proc ra0 . lra
     Apply PROC to each tuple of elements of ARRAY0 ... in row-major order.  The value returned is unspecified.

array-index-map!
 -- Scheme Procedure: array-index-map! ra proc
     Apply PROC to the indices of each element of ARRAY in turn, storing the result in the corresponding element.  The value returned and the order of application are unspecified.

     One can implement ARRAY-INDEXES as

          (define (array-indexes array)
              (let ((ra (apply make-array #f (array-shape array))))
                (array-index-map! ra (lambda x x))
                ra))

     Another example:

          (define (apl:index-generator n)
              (let ((v (make-uniform-vector n 1)))
                (array-index-map! v (lambda (i) i))
                v))

uniform-vector-length
 -- Scheme Procedure: uniform-vector-length v
     Return the number of elements in UVE.

array?
 -- Scheme Procedure: array? v [prot]
     Return #t if the OBJ is an array, and #f if not.  The PROTOTYPE argument is used with uniform arrays and is described elsewhere.

array-rank
 -- Scheme Procedure: array-rank ra
     Return the number of dimensions of OBJ.  If OBJ is not an array, 0 is returned.

array-dimensions
 -- Scheme Procedure: array-dimensions ra
     Array-dimensions is similar to array-shape but replaces elements with a 0 minimum with one greater than the maximum. So:

          (array-dimensions (make-array 'foo '(-1 3) 5)) => ((-1 3) 5)

shared-array-root
 -- Scheme Procedure: shared-array-root ra
     Return the root vector of a shared array.

shared-array-offset
 -- Scheme Procedure: shared-array-offset ra
     Return the root vector index of the first element in the array.

shared-array-increments
 -- Scheme Procedure: shared-array-increments ra
     For each dimension, return the distance between elements in the root vector.

dimensions->uniform-array
 -- Scheme Procedure: dimensions->uniform-array dims prot [fill]
 -- Scheme Procedure: make-uniform-vector length prototype [fill]
     Create and return a uniform array or vector of type corresponding to PROTOTYPE with dimensions DIMS or length LENGTH.  If FILL is supplied, it's used to fill the array, otherwise PROTOTYPE is used.

make-shared-array
 -- Scheme Procedure: make-shared-array oldra mapfunc . dims
     make-shared-array can be used to create shared subarrays of other arrays.  The MAPPER is a function that translates coordinates in the new array into coordinates in the old array.  A MAPPER must be linear, and its range must stay within the bounds of the old array, but it can be otherwise arbitrary.  A simple example:

          (define fred (make-array #f 8 8))
          (define freds-diagonal
            (make-shared-array fred (lambda (i) (list i i)) 8))
          (array-set! freds-diagonal 'foo 3)
          (array-ref fred 3 3) => foo
          (define freds-center
            (make-shared-array fred (lambda (i j) (list (+ 3 i) (+ 3 j))) 2 2))
          (array-ref freds-center 0 0) => foo

transpose-array
 -- Scheme Procedure: transpose-array ra . args
     Return an array sharing contents with ARRAY, but with dimensions arranged in a different order.  There must be one DIM argument for each dimension of ARRAY. DIM0, DIM1, ... should be integers between 0 and the rank of the array to be returned.  Each integer in that range must appear at least once in the argument list.

     The values of DIM0, DIM1, ... correspond to dimensions in the array to be returned, their positions in the argument list to dimensions of ARRAY.  Several DIMs may have the same value, in which case the returned array will have smaller rank than ARRAY.

          (transpose-array '#2((a b) (c d)) 1 0) => #2((a c) (b d))
          (transpose-array '#2((a b) (c d)) 0 0) => #1(a d)
          (transpose-array '#3(((a b c) (d e f)) ((1 2 3) (4 5 6))) 1 1 0) =>
                          #2((a 4) (b 5) (c 6))

enclose-array
 -- Scheme Procedure: enclose-array ra . axes
     DIM0, DIM1 ... should be nonnegative integers less than the rank of ARRAY.  ENCLOSE-ARRAY returns an array resembling an array of shared arrays.  The dimensions of each shared array are the same as the DIMth dimensions of the original array, the dimensions of the outer array are the same as those of the original array that did not match a DIM.

     An enclosed array is not a general Scheme array.  Its elements may not be set using array-set!.  Two references to the same element of an enclosed array will be equal? but will not in general be eq?.  The value returned by ARRAY-PROTOTYPE when given an enclosed array is unspecified.

     examples:

          (enclose-array '#3(((a b c) (d e f)) ((1 2 3) (4 5 6))) 1) =>
             #<enclosed-array (#1(a d) #1(b e) #1(c f)) (#1(1 4) #1(2 5) #1(3 6))>

          (enclose-array '#3(((a b c) (d e f)) ((1 2 3) (4 5 6))) 1 0) =>
             #<enclosed-array #2((a 1) (d 4)) #2((b 2) (e 5)) #2((c 3) (f 6))>

array-in-bounds?
 -- Scheme Procedure: array-in-bounds? v . args
     Return #t if its arguments would be acceptable to array-ref.

array-ref
 -- Scheme Procedure: array-ref
     implemented by the C function "scm_uniform_vector_ref"

uniform-vector-ref
 -- Scheme Procedure: uniform-vector-ref v args
 -- Scheme Procedure: array-ref v . args
     Return the element at the (index1, index2) element in ARRAY.

uniform-array-set1!
 -- Scheme Procedure: uniform-array-set1!
     implemented by the C function "scm_array_set_x"

array-set!
 -- Scheme Procedure: array-set! v obj . args
 -- Scheme Procedure: uniform-array-set1! v obj args
     Set the element at the (index1, index2) element in ARRAY to NEW-VALUE.  The value returned by array-set! is unspecified.

array-contents
 -- Scheme Procedure: array-contents ra [strict]
     If ARRAY may be unrolled into a one dimensional shared array without changing their order (last subscript changing fastest), then array-contents returns that shared array, otherwise it returns #f.  All arrays made by MAKE-ARRAY and MAKE-UNIFORM-ARRAY may be unrolled, some arrays made by MAKE-SHARED-ARRAY may not be.

     If the optional argument STRICT is provided, a shared array will be returned only if its elements are stored internally contiguous in memory.

uniform-array-read!
 -- Scheme Procedure: uniform-array-read! ra [port_or_fd [start [end]]]
 -- Scheme Procedure: uniform-vector-read! uve [port-or-fdes] [start] [end]
     Attempt to read all elements of URA, in lexicographic order, as binary objects from PORT-OR-FDES. If an end of file is encountered during uniform-array-read! the objects up to that point only are put into URA (starting at the beginning) and the remainder of the array is unchanged.

     The optional arguments START and END allow a specified region of a vector (or linearized array) to be read, leaving the remainder of the vector unchanged.

     uniform-array-read! returns the number of objects read. PORT-OR-FDES may be omitted, in which case it defaults to the value returned by (current-input-port).

uniform-array-write
 -- Scheme Procedure: uniform-array-write v [port_or_fd [start [end]]]
 -- Scheme Procedure: uniform-vector-write uve [port-or-fdes] [start] [end]
     Writes all elements of URA as binary objects to PORT-OR-FDES.

     The optional arguments START and END allow a specified region of a vector (or linearized array) to be written.

     The number of objects actually written is returned. PORT-OR-FDES may be omitted, in which case it defaults to the value returned by (current-output-port).

bit-count
 -- Scheme Procedure: bit-count b bitvector
     Return the number of occurrences of the boolean B in BITVECTOR.

bit-position
 -- Scheme Procedure: bit-position item v k
     Return the minimum index of an occurrence of BOOL in BV which is at least K.  If no BOOL occurs within the specified range #f is returned.

bit-set*!
 -- Scheme Procedure: bit-set*! v kv obj
     If uve is a bit-vector BV and uve must be of the same length.  If BOOL is #t, uve is OR'ed into BV; If BOOL is #f, the inversion of uve is AND'ed into BV.

     If uve is a unsigned integer vector all the elements of uve must be between 0 and the length of BV.  The bits of BV corresponding to the indexes in uve are set to BOOL.  The return value is unspecified.

bit-count*
 -- Scheme Procedure: bit-count* v kv obj
     Return

          (bit-count (bit-set*! (if bool bv (bit-invert! bv)) uve #t) #t).

     BV is not modified.

bit-invert!
 -- Scheme Procedure: bit-invert! v
     Modify BV by replacing each element with its negation.

array->list
 -- Scheme Procedure: array->list v
     Return a list consisting of all the elements, in order, of ARRAY.

list->uniform-array
 -- Scheme Procedure: list->uniform-array ndim prot lst
 -- Scheme Procedure: list->uniform-vector prot lst
     Return a uniform array of the type indicated by prototype PROT with elements the same as those of LST. Elements must be of the appropriate type, no coercions are done.

array-prototype
 -- Scheme Procedure: array-prototype ra
     Return an object that would produce an array of the same type as ARRAY, if used as the PROTOTYPE for make-uniform-array.

chown
 -- Scheme Procedure: chown object owner group
     Change the ownership and group of the file referred to by OBJECT to the integer values OWNER and GROUP.  OBJECT can be a string containing a file name or, if the platform supports fchown, a port or integer file descriptor which is open on the file.  The return value is unspecified.

     If OBJECT is a symbolic link, either the ownership of the link or the ownership of the referenced file will be changed depending on the operating system (lchown is unsupported at present).  If OWNER or GROUP is specified as -1, then that ID is not changed.

chmod
 -- Scheme Procedure: chmod object mode
     Changes the permissions of the file referred to by OBJ. OBJ can be a string containing a file name or a port or integer file descriptor which is open on a file (in which case fchmod is used as the underlying system call). MODE specifies the new permissions as a decimal number, e.g., (chmod "foo" #o755). The return value is unspecified.

umask
 -- Scheme Procedure: umask [mode]
     If MODE is omitted, returns a decimal number representing the current file creation mask.  Otherwise the file creation mask is set to MODE and the previous value is returned.

     E.g., (umask #o022) sets the mask to octal 22, decimal 18.

open-fdes
 -- Scheme Procedure: open-fdes path flags [mode]
     Similar to open but return a file descriptor instead of a port.

open
 -- Scheme Procedure: open path flags [mode]
     Open the file named by PATH for reading and/or writing. FLAGS is an integer specifying how the file should be opened. MODE is an integer specifying the permission bits of the file, if it needs to be created, before the umask is applied.  The default is 666 (Unix itself has no default).

     FLAGS can be constructed by combining variables using logior. Basic flags are:

      -- Variable: O_RDONLY
          Open the file read-only.

      -- Variable: O_WRONLY
          Open the file write-only.

      -- Variable: O_RDWR
          Open the file read/write.

      -- Variable: O_APPEND
          Append to the file instead of truncating.

      -- Variable: O_CREAT
          Create the file if it does not already exist.

     See the Unix documentation of the open system call for additional flags.

close
 -- Scheme Procedure: close fd_or_port
     Similar to close-port (see close-port), but also works on file descriptors.  A side effect of closing a file descriptor is that any ports using that file descriptor are moved to a different file descriptor and have their revealed counts set to zero.

close-fdes
 -- Scheme Procedure: close-fdes fd
     A simple wrapper for the close system call. Close file descriptor FD, which must be an integer. Unlike close (see close), the file descriptor will be closed even if a port is using it. The return value is unspecified.

stat
 -- Scheme Procedure: stat object
     Return an object containing various information about the file determined by OBJ.  OBJ can be a string containing a file name or a port or integer file descriptor which is open on a file (in which case fstat is used as the underlying system call).

     The object returned by stat can be passed as a single parameter to the following procedures, all of which return integers:

     stat:dev
          The device containing the file.

     stat:ino
          The file serial number, which distinguishes this file from all other files on the same device.

     stat:mode
          The mode of the file.  This includes file type information and the file permission bits.  See stat:type and stat:perms below.

     stat:nlink
          The number of hard links to the file.

     stat:uid
          The user ID of the file's owner.

     stat:gid
          The group ID of the file.

     stat:rdev
          Device ID; this entry is defined only for character or block special files.

     stat:size
          The size of a regular file in bytes.

     stat:atime
          The last access time for the file.

     stat:mtime
          The last modification time for the file.

     stat:ctime
          The last modification time for the attributes of the file.

     stat:blksize
          The optimal block size for reading or writing the file, in bytes.

     stat:blocks
          The amount of disk space that the file occupies measured in units of 512 byte blocks.

     In addition, the following procedures return the information from stat:mode in a more convenient form:

     stat:type
          A symbol representing the type of file.  Possible values are regular, directory, symlink, block-special, char-special, fifo, socket and unknown

     stat:perms
          An integer representing the access permission bits.

link
 -- Scheme Procedure: link oldpath newpath
     Creates a new name NEWPATH in the file system for the file named by OLDPATH.  If OLDPATH is a symbolic link, the link may or may not be followed depending on the system.

rename-file
 -- Scheme Procedure: rename-file oldname newname
     Renames the file specified by OLDNAME to NEWNAME. The return value is unspecified.

delete-file
 -- Scheme Procedure: delete-file str
     Deletes (or "unlinks") the file specified by PATH.

mkdir
 -- Scheme Procedure: mkdir path [mode]
     Create a new directory named by PATH.  If MODE is omitted then the permissions of the directory file are set using the current umask.  Otherwise they are set to the decimal value specified with MODE.  The return value is unspecified.

rmdir
 -- Scheme Procedure: rmdir path
     Remove the existing directory named by PATH.  The directory must be empty for this to succeed.  The return value is unspecified.

directory-stream?
 -- Scheme Procedure: directory-stream? obj
     Return a boolean indicating whether OBJECT is a directory stream as returned by opendir.

opendir
 -- Scheme Procedure: opendir dirname
     Open the directory specified by PATH and return a directory stream.

readdir
 -- Scheme Procedure: readdir port
     Return (as a string) the next directory entry from the directory stream STREAM.  If there is no remaining entry to be read then the end of file object is returned.

rewinddir
 -- Scheme Procedure: rewinddir port
     Reset the directory port STREAM so that the next call to readdir will return the first directory entry.

closedir
 -- Scheme Procedure: closedir port
     Close the directory stream STREAM. The return value is unspecified.

chdir
 -- Scheme Procedure: chdir str
     Change the current working directory to PATH. The return value is unspecified.

getcwd
 -- Scheme Procedure: getcwd
     Return the name of the current working directory.

select
 -- Scheme Procedure: select reads writes excepts [secs [usecs]]
     This procedure has a variety of uses: waiting for the ability to provide input, accept output, or the existence of exceptional conditions on a collection of ports or file descriptors, or waiting for a timeout to occur. It also returns if interrupted by a signal.

     READS, WRITES and EXCEPTS can be lists or vectors, with each member a port or a file descriptor. The value returned is a list of three corresponding lists or vectors containing only the members which meet the specified requirement.  The ability of port buffers to provide input or accept output is taken into account. Ordering of the input lists or vectors is not preserved.

     The optional arguments SECS and USECS specify the timeout.  Either SECS can be specified alone, as either an integer or a real number, or both SECS and USECS can be specified as integers, in which case USECS is an additional timeout expressed in microseconds.  If SECS is omitted or is #f then select will wait for as long as it takes for one of the other conditions to be satisfied.

     The scsh version of select differs as follows: Only vectors are accepted for the first three arguments. The USECS argument is not supported. Multiple values are returned instead of a list. Duplicates in the input vectors appear only once in output. An additional select! interface is provided.

fcntl
 -- Scheme Procedure: fcntl object cmd [value]
     Apply COMMAND to the specified file descriptor or the underlying file descriptor of the specified port.  VALUE is an optional integer argument.

     Values for COMMAND are:

     F_DUPFD
          Duplicate a file descriptor

     F_GETFD
          Get flags associated with the file descriptor.

     F_SETFD
          Set flags associated with the file descriptor to VALUE.

     F_GETFL
          Get flags associated with the open file.

     F_SETFL
          Set flags associated with the open file to VALUE

     F_GETOWN
          Get the process ID of a socket's owner, for SIGIO signals.

     F_SETOWN
          Set the process that owns a socket to VALUE, for SIGIO signals.

     FD_CLOEXEC
          The value used to indicate the "close on exec" flag with F_GETFL or F_SETFL.

fsync
 -- Scheme Procedure: fsync object
     Copies any unwritten data for the specified output file descriptor to disk. If PORT/FD is a port, its buffer is flushed before the underlying file descriptor is fsync'd. The return value is unspecified.

symlink
 -- Scheme Procedure: symlink oldpath newpath
     Create a symbolic link named PATH-TO with the value (i.e., pointing to) PATH-FROM.  The return value is unspecified.

readlink
 -- Scheme Procedure: readlink path
     Return the value of the symbolic link named by PATH (a string), i.e., the file that the link points to.

lstat
 -- Scheme Procedure: lstat str
     Similar to stat, but does not follow symbolic links, i.e., it will return information about a symbolic link itself, not the file it points to.  PATH must be a string.

copy-file
 -- Scheme Procedure: copy-file oldfile newfile
     Copy the file specified by PATH-FROM to PATH-TO. The return value is unspecified.

dirname
 -- Scheme Procedure: dirname filename
     Return the directory name component of the file name FILENAME. If FILENAME does not contain a directory component, . is returned.

basename
 -- Scheme Procedure: basename filename [suffix]
     Return the base name of the file name FILENAME. The base name is the file name without any directory components. If SUFFIX is provided, and is equal to the end of BASENAME, it is removed also.

pipe
 -- Scheme Procedure: pipe
     Return a newly created pipe: a pair of ports which are linked together on the local machine.  The car is the input port and the cdr is the output port.  Data written (and flushed) to the output port can be read from the input port. Pipes are commonly used for communication with a newly forked child process.  The need to flush the output port can be avoided by making it unbuffered using setvbuf.

     Writes occur atomically provided the size of the data in bytes is not greater than the value of PIPE_BUF.  Note that the output port is likely to block if too much data (typically equal to PIPE_BUF) has been written but not yet read from the input port.

getgroups
 -- Scheme Procedure: getgroups
     Return a vector of integers representing the current supplementary group IDs.

getpw
 -- Scheme Procedure: getpw [user]
     Look up an entry in the user database.  OBJ can be an integer, a string, or omitted, giving the behaviour of getpwuid, getpwnam or getpwent respectively.

setpw
 -- Scheme Procedure: setpw [arg]
     If called with a true argument, initialize or reset the password data stream.  Otherwise, close the stream.  The setpwent and endpwent procedures are implemented on top of this.

getgr
 -- Scheme Procedure: getgr [name]
     Look up an entry in the group database.  OBJ can be an integer, a string, or omitted, giving the behaviour of getgrgid, getgrnam or getgrent respectively.

setgr
 -- Scheme Procedure: setgr [arg]
     If called with a true argument, initialize or reset the group data stream.  Otherwise, close the stream.  The setgrent and endgrent procedures are implemented on top of this.

kill
 -- Scheme Procedure: kill pid sig
     Sends a signal to the specified process or group of processes.

     PID specifies the processes to which the signal is sent:

     PID greater than 0
          The process whose identifier is PID.

     PID equal to 0
          All processes in the current process group.

     PID less than -1
          The process group whose identifier is -PID

     PID equal to -1
          If the process is privileged, all processes except for some special system processes.  Otherwise, all processes with the current effective user ID.

     SIG should be specified using a variable corresponding to the Unix symbolic name, e.g.,

      -- Variable: SIGHUP
          Hang-up signal.

      -- Variable: SIGINT
          Interrupt signal.

waitpid
 -- Scheme Procedure: waitpid pid [options]
     This procedure collects status information from a child process which has terminated or (optionally) stopped.  Normally it will suspend the calling process until this can be done.  If more than one child process is eligible then one will be chosen by the operating system.

     The value of PID determines the behaviour:

     PID greater than 0
          Request status information from the specified child process.

     PID equal to -1 or WAIT_ANY
          Request status information for any child process.

     PID equal to 0 or WAIT_MYPGRP
          Request status information for any child process in the current process group.

     PID less than -1
          Request status information for any child process whose process group ID is -PID.

     The OPTIONS argument, if supplied, should be the bitwise OR of the values of zero or more of the following variables:

      -- Variable: WNOHANG
          Return immediately even if there are no child processes to be collected.

      -- Variable: WUNTRACED
          Report status information for stopped processes as well as terminated processes.

     The return value is a pair containing:

      1. The process ID of the child process, or 0 if WNOHANG was specified and no process was collected.

      2. The integer status value.

status:exit-val
 -- Scheme Procedure: status:exit-val status
     Return the exit status value, as would be set if a process ended normally through a call to exit or _exit, if any, otherwise #f.

status:term-sig
 -- Scheme Procedure: status:term-sig status
     Return the signal number which terminated the process, if any, otherwise #f.

status:stop-sig
 -- Scheme Procedure: status:stop-sig status
     Return the signal number which stopped the process, if any, otherwise #f.

getppid
 -- Scheme Procedure: getppid
     Return an integer representing the process ID of the parent process.

getuid
 -- Scheme Procedure: getuid
     Return an integer representing the current real user ID.

getgid
 -- Scheme Procedure: getgid
     Return an integer representing the current real group ID.

geteuid
 -- Scheme Procedure: geteuid
     Return an integer representing the current effective user ID. If the system does not support effective IDs, then the real ID is returned.  (feature? 'EIDs) reports whether the system supports effective IDs.

getegid
 -- Scheme Procedure: getegid
     Return an integer representing the current effective group ID. If the system does not support effective IDs, then the real ID is returned.  (feature? 'EIDs) reports whether the system supports effective IDs.

setuid
 -- Scheme Procedure: setuid id
     Sets both the real and effective user IDs to the integer ID, provided the process has appropriate privileges. The return value is unspecified.

setgid
 -- Scheme Procedure: setgid id
     Sets both the real and effective group IDs to the integer ID, provided the process has appropriate privileges. The return value is unspecified.

seteuid
 -- Scheme Procedure: seteuid id
     Sets the effective user ID to the integer ID, provided the process has appropriate privileges.  If effective IDs are not supported, the real ID is set instead -- (feature? 'EIDs) reports whether the system supports effective IDs. The return value is unspecified.

setegid
 -- Scheme Procedure: setegid id
     Sets the effective group ID to the integer ID, provided the process has appropriate privileges.  If effective IDs are not supported, the real ID is set instead -- (feature? 'EIDs) reports whether the system supports effective IDs. The return value is unspecified.

getpgrp
 -- Scheme Procedure: getpgrp
     Return an integer representing the current process group ID. This is the POSIX definition, not BSD.

setpgid
 -- Scheme Procedure: setpgid pid pgid
     Move the process PID into the process group PGID.  PID or PGID must be integers: they can be zero to indicate the ID of the current process. Fails on systems that do not support job control. The return value is unspecified.

setsid
 -- Scheme Procedure: setsid
     Creates a new session.  The current process becomes the session leader and is put in a new process group.  The process will be detached from its controlling terminal if it has one. The return value is an integer representing the new process group ID.

ttyname
 -- Scheme Procedure: ttyname port
     Return a string with the name of the serial terminal device underlying PORT.

ctermid
 -- Scheme Procedure: ctermid
     Return a string containing the file name of the controlling terminal for the current process.

tcgetpgrp
 -- Scheme Procedure: tcgetpgrp port
     Return the process group ID of the foreground process group associated with the terminal open on the file descriptor underlying PORT.

     If there is no foreground process group, the return value is a number greater than 1 that does not match the process group ID of any existing process group.  This can happen if all of the processes in the job that was formerly the foreground job have terminated, and no other job has yet been moved into the foreground.

tcsetpgrp
 -- Scheme Procedure: tcsetpgrp port pgid
     Set the foreground process group ID for the terminal used by the file descriptor underlying PORT to the integer PGID. The calling process must be a member of the same session as PGID and must have the same controlling terminal.  The return value is unspecified.

execl
 -- Scheme Procedure: execl filename . args
     Executes the file named by PATH as a new process image. The remaining arguments are supplied to the process; from a C program they are accessible as the argv argument to main. Conventionally the first ARG is the same as PATH. All arguments must be strings.

     If ARG is missing, PATH is executed with a null argument list, which may have system-dependent side-effects.

     This procedure is currently implemented using the execv system call, but we call it execl because of its Scheme calling interface.

execlp
 -- Scheme Procedure: execlp filename . args
     Similar to execl, however if FILENAME does not contain a slash then the file to execute will be located by searching the directories listed in the PATH environment variable.

     This procedure is currently implemented using the execvp system call, but we call it execlp because of its Scheme calling interface.

execle
 -- Scheme Procedure: execle filename env . args
     Similar to execl, but the environment of the new process is specified by ENV, which must be a list of strings as returned by the environ procedure.

     This procedure is currently implemented using the execve system call, but we call it execle because of its Scheme calling interface.

primitive-fork
 -- Scheme Procedure: primitive-fork
     Creates a new "child" process by duplicating the current "parent" process. In the child the return value is 0.  In the parent the return value is the integer process ID of the child.

     This procedure has been renamed from fork to avoid a naming conflict with the scsh fork.

uname
 -- Scheme Procedure: uname
     Return an object with some information about the computer system the program is running on.

environ
 -- Scheme Procedure: environ [env]
     If ENV is omitted, return the current environment (in the Unix sense) as a list of strings.  Otherwise set the current environment, which is also the default environment for child processes, to the supplied list of strings.  Each member of ENV should be of the form NAME=VALUE and values of NAME should not be duplicated.  If ENV is supplied then the return value is unspecified.

tmpnam
 -- Scheme Procedure: tmpnam
     Return a name in the file system that does not match any existing file.  However there is no guarantee that another process will not create the file after tmpnam is called. Care should be taken if opening the file, e.g., use the O_EXCL open flag or use mkstemp! instead.

mkstemp!
 -- Scheme Procedure: mkstemp! tmpl
     Create a new unique file in the file system and returns a new buffered port open for reading and writing to the file. TMPL is a string specifying where the file should be created: it must end with XXXXXX and will be changed in place to return the name of the temporary file.

utime
 -- Scheme Procedure: utime pathname [actime [modtime]]
     utime sets the access and modification times for the file named by PATH.  If ACTIME or MODTIME is not supplied, then the current time is used.  ACTIME and MODTIME must be integer time values as returned by the current-time procedure.

          (utime "foo" (- (current-time) 3600))

     will set the access time to one hour in the past and the modification time to the current time.

access?
 -- Scheme Procedure: access? path how
     Return #t if PATH corresponds to an existing file and the current process has the type of access specified by HOW, otherwise #f.  HOW should be specified using the values of the variables listed below.  Multiple values can be combined using a bitwise or, in which case #t will only be returned if all accesses are granted.

     Permissions are checked using the real id of the current process, not the effective id, although it's the effective id which determines whether the access would actually be granted.

      -- Variable: R_OK
          test for read permission.

      -- Variable: W_OK
          test for write permission.

      -- Variable: X_OK
          test for execute permission.

      -- Variable: F_OK
          test for existence of the file.

getpid
 -- Scheme Procedure: getpid
     Return an integer representing the current process ID.

putenv
 -- Scheme Procedure: putenv str
     Modifies the environment of the current process, which is also the default environment inherited by child processes.

     If STRING is of the form NAME=VALUE then it will be written directly into the environment, replacing any existing environment string with name matching NAME.  If STRING does not contain an equal sign, then any existing string with name matching STRING will be removed.

     The return value is unspecified.

setlocale
 -- Scheme Procedure: setlocale category [locale]
     If LOCALE is omitted, return the current value of the specified locale category as a system-dependent string. CATEGORY should be specified using the values LC_COLLATE, LC_ALL etc.

     Otherwise the specified locale category is set to the string LOCALE and the new value is returned as a system-dependent string.  If LOCALE is an empty string, the locale will be set using environment variables.

mknod
 -- Scheme Procedure: mknod path type perms dev
     Creates a new special file, such as a file corresponding to a device. PATH specifies the name of the file.  TYPE should be one of the following symbols: regular, directory, symlink, block-special, char-special, fifo, or socket.  PERMS (an integer) specifies the file permissions. DEV (an integer) specifies which device the special file refers to.  Its exact interpretation depends on the kind of special file being created.

     E.g.,

          (mknod "/dev/fd0" 'block-special #o660 (+ (* 2 256) 2))

     The return value is unspecified.

nice
 -- Scheme Procedure: nice incr
     Increment the priority of the current process by INCR.  A higher priority value means that the process runs less often. The return value is unspecified.

sync
 -- Scheme Procedure: sync
     Flush the operating system disk buffers. The return value is unspecified.

crypt
 -- Scheme Procedure: crypt key salt
     Encrypt KEY using SALT as the salt value to the crypt(3) library call.

chroot
 -- Scheme Procedure: chroot path
     Change the root directory to that specified in PATH. This directory will be used for path names beginning with /.  The root directory is inherited by all children of the current process.  Only the superuser may change the root directory.

getlogin
 -- Scheme Procedure: getlogin
     Return a string containing the name of the user logged in on the controlling terminal of the process, or #f if this information cannot be obtained.

cuserid
 -- Scheme Procedure: cuserid
     Return a string containing a user name associated with the effective user id of the process.  Return #f if this information cannot be obtained.

getpriority
 -- Scheme Procedure: getpriority which who
     Return the scheduling priority of the process, process group or user, as indicated by WHICH and WHO. WHICH is one of the variables PRIO_PROCESS, PRIO_PGRP or PRIO_USER, and WHO is interpreted relative to WHICH (a process identifier for PRIO_PROCESS, process group identifier for PRIO_PGRP, and a user identifier for PRIO_USER.  A zero value of WHO denotes the current process, process group, or user.  Return the highest priority (lowest numerical value) of any of the specified processes.

setpriority
 -- Scheme Procedure: setpriority which who prio
     Set the scheduling priority of the process, process group or user, as indicated by WHICH and WHO. WHICH is one of the variables PRIO_PROCESS, PRIO_PGRP or PRIO_USER, and WHO is interpreted relative to WHICH (a process identifier for PRIO_PROCESS, process group identifier for PRIO_PGRP, and a user identifier for PRIO_USER.  A zero value of WHO denotes the current process, process group, or user. PRIO is a value in the range -20 and 20, the default priority is 0; lower priorities cause more favorable scheduling.  Sets the priority of all of the specified processes.  Only the super-user may lower priorities. The return value is not specified.

getpass
 -- Scheme Procedure: getpass prompt
     Display PROMPT to the standard error output and read a password from /dev/tty.  If this file is not accessible, it reads from standard input.  The password may be up to 127 characters in length.  Additional characters and the terminating newline character are discarded.  While reading the password, echoing and the generation of signals by special characters is disabled.

flock
 -- Scheme Procedure: flock file operation
     Apply or remove an advisory lock on an open file. OPERATION specifies the action to be done:

     LOCK_SH
          Shared lock.  More than one process may hold a shared lock for a given file at a given time.

     LOCK_EX
          Exclusive lock.  Only one process may hold an exclusive lock for a given file at a given time.

     LOCK_UN
          Unlock the file.

     LOCK_NB
          Don't block when locking.  May be specified by bitwise OR'ing it to one of the other operations.

     The return value is not specified. FILE may be an open file descriptor or an open file descriptor port.

sethostname
 -- Scheme Procedure: sethostname name
     Set the host name of the current processor to NAME. May only be used by the superuser.  The return value is not specified.

gethostname
 -- Scheme Procedure: gethostname
     Return the host name of the current processor.

gethost
 -- Scheme Procedure: gethost [host]
 -- Scheme Procedure: gethostbyname hostname
 -- Scheme Procedure: gethostbyaddr address
     Look up a host by name or address, returning a host object.  The gethost procedure will accept either a string name or an integer address; if given no arguments, it behaves like gethostent (see below).  If a name or address is supplied but the address can not be found, an error will be thrown to one of the keys: host-not-found, try-again, no-recovery or no-data, corresponding to the equivalent h_error values. Unusual conditions may result in errors thrown to the system-error or misc_error keys.

getnet
 -- Scheme Procedure: getnet [net]
 -- Scheme Procedure: getnetbyname net-name
 -- Scheme Procedure: getnetbyaddr net-number
     Look up a network by name or net number in the network database.  The NET-NAME argument must be a string, and the NET-NUMBER argument must be an integer.  getnet will accept either type of argument, behaving like getnetent (see below) if no arguments are given.

getproto
 -- Scheme Procedure: getproto [protocol]
 -- Scheme Procedure: getprotobyname name
 -- Scheme Procedure: getprotobynumber number
     Look up a network protocol by name or by number.  getprotobyname takes a string argument, and getprotobynumber takes an integer argument.  getproto will accept either type, behaving like getprotoent (see below) if no arguments are supplied.

getserv
 -- Scheme Procedure: getserv [name [protocol]]
 -- Scheme Procedure: getservbyname name protocol
 -- Scheme Procedure: getservbyport port protocol
     Look up a network service by name or by service number, and return a network service object.  The PROTOCOL argument specifies the name of the desired protocol; if the protocol found in the network service database does not match this name, a system error is signalled.

     The getserv procedure will take either a service name or number as its first argument; if given no arguments, it behaves like getservent (see below).

sethost
 -- Scheme Procedure: sethost [stayopen]
     If STAYOPEN is omitted, this is equivalent to endhostent. Otherwise it is equivalent to sethostent stayopen.

setnet
 -- Scheme Procedure: setnet [stayopen]
     If STAYOPEN is omitted, this is equivalent to endnetent. Otherwise it is equivalent to setnetent stayopen.

setproto
 -- Scheme Procedure: setproto [stayopen]
     If STAYOPEN is omitted, this is equivalent to endprotoent. Otherwise it is equivalent to setprotoent stayopen.

setserv
 -- Scheme Procedure: setserv [stayopen]
     If STAYOPEN is omitted, this is equivalent to endservent. Otherwise it is equivalent to setservent stayopen.

htons
 -- Scheme Procedure: htons value
     Convert a 16 bit quantity from host to network byte ordering. VALUE is packed into 2 bytes, which are then converted and returned as a new integer.

ntohs
 -- Scheme Procedure: ntohs value
     Convert a 16 bit quantity from network to host byte ordering. VALUE is packed into 2 bytes, which are then converted and returned as a new integer.

htonl
 -- Scheme Procedure: htonl value
     Convert a 32 bit quantity from host to network byte ordering. VALUE is packed into 4 bytes, which are then converted and returned as a new integer.

ntohl
 -- Scheme Procedure: ntohl value
     Convert a 32 bit quantity from network to host byte ordering. VALUE is packed into 4 bytes, which are then converted and returned as a new integer.

inet-aton
 -- Scheme Procedure: inet-aton address
     Convert an IPv4 Internet address from printable string (dotted decimal notation) to an integer.  E.g.,

          (inet-aton "127.0.0.1") => 2130706433

inet-ntoa
 -- Scheme Procedure: inet-ntoa inetid
     Convert an IPv4 Internet address to a printable (dotted decimal notation) string.  E.g.,

          (inet-ntoa 2130706433) => "127.0.0.1"

inet-netof
 -- Scheme Procedure: inet-netof address
     Return the network number part of the given IPv4 Internet address.  E.g.,

          (inet-netof 2130706433) => 127

inet-lnaof
 -- Scheme Procedure: inet-lnaof address
     Return the local-address-with-network part of the given IPv4 Internet address, using the obsolete class A/B/C system. E.g.,

          (inet-lnaof 2130706433) => 1

inet-makeaddr
 -- Scheme Procedure: inet-makeaddr net lna
     Make an IPv4 Internet address by combining the network number NET with the local-address-within-network number LNA.  E.g.,

          (inet-makeaddr 127 1) => 2130706433

inet-pton
 -- Scheme Procedure: inet-pton family address
     Convert a string containing a printable network address to an integer address.  Note that unlike the C version of this function, the result is an integer with normal host byte ordering. FAMILY can be AF_INET or AF_INET6.  E.g.,

          (inet-pton AF_INET "127.0.0.1") => 2130706433
          (inet-pton AF_INET6 "::1") => 1

inet-ntop
 -- Scheme Procedure: inet-ntop family address
     Convert a network address into a printable string. Note that unlike the C version of this function, the input is an integer with normal host byte ordering. FAMILY can be AF_INET or AF_INET6.  E.g.,

          (inet-ntop AF_INET 2130706433) => "127.0.0.1"
          (inet-ntop AF_INET6 (- (expt 2 128) 1)) =>
          ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff

socket
 -- Scheme Procedure: socket family style proto
     Return a new socket port of the type specified by FAMILY, STYLE and PROTO.  All three parameters are integers.  Supported values for FAMILY are AF_UNIX, AF_INET and AF_INET6. Typical values for STYLE are SOCK_STREAM, SOCK_DGRAM and SOCK_RAW.

     PROTO can be obtained from a protocol name using getprotobyname.  A value of zero specifies the default protocol, which is usually right.

     A single socket port cannot by used for communication until it has been connected to another socket.

socketpair
 -- Scheme Procedure: socketpair family style proto
     Return a pair of connected (but unnamed) socket ports of the type specified by FAMILY, STYLE and PROTO. Many systems support only socket pairs of the AF_UNIX family.  Zero is likely to be the only meaningful value for PROTO.

getsockopt
 -- Scheme Procedure: getsockopt sock level optname
     Return the value of a particular socket option for the socket port SOCK.  LEVEL is an integer code for type of option being requested, e.g., SOL_SOCKET for socket-level options.  OPTNAME is an integer code for the option required and should be specified using one of the symbols SO_DEBUG, SO_REUSEADDR etc.

     The returned value is typically an integer but SO_LINGER returns a pair of integers.

setsockopt
 -- Scheme Procedure: setsockopt sock level optname value
     Set the value of a particular socket option for the socket port SOCK.  LEVEL is an integer code for type of option being set, e.g., SOL_SOCKET for socket-level options. OPTNAME is an integer code for the option to set and should be specified using one of the symbols SO_DEBUG, SO_REUSEADDR etc. VALUE is the value to which the option should be set.  For most options this must be an integer, but for SO_LINGER it must be a pair.

     The return value is unspecified.

shutdown
 -- Scheme Procedure: shutdown sock how
     Sockets can be closed simply by using close-port. The shutdown procedure allows reception or transmission on a connection to be shut down individually, according to the parameter HOW:

     0
          Stop receiving data for this socket.  If further data arrives,  reject it.

     1
          Stop trying to transmit data from this socket.  Discard any data waiting to be sent.  Stop looking for acknowledgement of data already sent; don't retransmit it if it is lost.

     2
          Stop both reception and transmission.

     The return value is unspecified.

connect
 -- Scheme Procedure: connect sock fam address . args
     Initiate a connection from a socket using a specified address family to the address specified by ADDRESS and possibly ARGS. The format required for ADDRESS and ARGS depends on the family of the socket.

     For a socket of family AF_UNIX, only ADDRESS is specified and must be a string with the filename where the socket is to be created.

     For a socket of family AF_INET, ADDRESS must be an integer IPv4 host address and ARGS must be a single integer port number.

     For a socket of family AF_INET6, ADDRESS must be an integer IPv6 host address and ARGS may be up to three integers: port [flowinfo] [scope_id], where flowinfo and scope_id default to zero.

     The return value is unspecified.

bind
 -- Scheme Procedure: bind sock fam address . args
     Assign an address to the socket port SOCK. Generally this only needs to be done for server sockets, so they know where to look for incoming connections.  A socket without an address will be assigned one automatically when it starts communicating.

     The format of ADDRESS and ARGS depends on the family of the socket.

     For a socket of family AF_UNIX, only ADDRESS is specified and must be a string with the filename where the socket is to be created.

     For a socket of family AF_INET, ADDRESS must be an integer IPv4 address and ARGS must be a single integer port number.

     The values of the following variables can also be used for ADDRESS:

      -- Variable: INADDR_ANY
          Allow connections from any address.

      -- Variable: INADDR_LOOPBACK
          The address of the local host using the loopback device.

      -- Variable: INADDR_BROADCAST
          The broadcast address on the local network.

      -- Variable: INADDR_NONE
          No address.

     For a socket of family AF_INET6, ADDRESS must be an integer IPv6 address and ARGS may be up to three integers: port [flowinfo] [scope_id], where flowinfo and scope_id default to zero.

     The return value is unspecified.

listen
 -- Scheme Procedure: listen sock backlog
     Enable SOCK to accept connection requests.  BACKLOG is an integer specifying the maximum length of the queue for pending connections. If the queue fills, new clients will fail to connect until the server calls accept to accept a connection from the queue.

     The return value is unspecified.

accept
 -- Scheme Procedure: accept sock
     Accept a connection on a bound, listening socket. If there are no pending connections in the queue, wait until one is available unless the non-blocking option has been set on the socket.

     The return value is a pair in which the car is a new socket port for the connection and the cdr is an object with address information about the client which initiated the connection.

     SOCK does not become part of the connection and will continue to accept new requests.

getsockname
 -- Scheme Procedure: getsockname sock
     Return the address of SOCK, in the same form as the object returned by accept.  On many systems the address of a socket in the AF_FILE namespace cannot be read.

getpeername
 -- Scheme Procedure: getpeername sock
     Return the address that SOCK is connected to, in the same form as the object returned by accept.  On many systems the address of a socket in the AF_FILE namespace cannot be read.

recv!
 -- Scheme Procedure: recv! sock buf [flags]
     Receive data from a socket port. SOCK must already be bound to the address from which data is to be received. BUF is a string into which the data will be written.  The size of BUF limits the amount of data which can be received: in the case of packet protocols, if a packet larger than this limit is encountered then some data will be irrevocably lost.

     The optional FLAGS argument is a value or bitwise OR of MSG_OOB, MSG_PEEK, MSG_DONTROUTE etc.

     The value returned is the number of bytes read from the socket.

     Note that the data is read directly from the socket file descriptor: any unread buffered port data is ignored.

send
 -- Scheme Procedure: send sock message [flags]
     Transmit the string MESSAGE on a socket port SOCK. SOCK must already be bound to a destination address.  The value returned is the number of bytes transmitted -- it's possible for this to be less than the length of MESSAGE if the socket is set to be non-blocking.  The optional FLAGS argument is a value or bitwise OR of MSG_OOB, MSG_PEEK, MSG_DONTROUTE etc.

     Note that the data is written directly to the socket file descriptor: any unflushed buffered port data is ignored.

recvfrom!
 -- Scheme Procedure: recvfrom! sock str [flags [start [end]]]
     Return data from the socket port SOCK and also information about where the data was received from. SOCK must already be bound to the address from which data is to be received.  str, is a string into which the data will be written.  The size of STR limits the amount of data which can be received: in the case of packet protocols, if a packet larger than this limit is encountered then some data will be irrevocably lost.

     The optional FLAGS argument is a value or bitwise OR of MSG_OOB, MSG_PEEK, MSG_DONTROUTE etc.

     The value returned is a pair: the car is the number of bytes read from the socket and the cdr an address object in the same form as returned by accept.  The address will given as #f if not available, as is usually the case for stream sockets.

     The START and END arguments specify a substring of STR to which the data should be written.

     Note that the data is read directly from the socket file descriptor: any unread buffered port data is ignored.

sendto
 -- Scheme Procedure: sendto sock message fam address . args_and_flags
     Transmit the string MESSAGE on the socket port SOCK.  The destination address is specified using the FAM, ADDRESS and ARGS_AND_FLAGS arguments, in a similar way to the connect procedure.  ARGS_AND_FLAGS contains the usual connection arguments optionally followed by a flags argument, which is a value or bitwise OR of MSG_OOB, MSG_PEEK, MSG_DONTROUTE etc.

     The value returned is the number of bytes transmitted -- it's possible for this to be less than the length of MESSAGE if the socket is set to be non-blocking. Note that the data is written directly to the socket file descriptor: any unflushed buffered port data is ignored.

regexp?
 -- Scheme Procedure: regexp? obj
     Return #t if OBJ is a compiled regular expression, or #f otherwise.

make-regexp
 -- Scheme Procedure: make-regexp pat . flags
     Compile the regular expression described by PAT, and return the compiled regexp structure.  If PAT does not describe a legal regular expression, make-regexp throws a regular-expression-syntax error.

     The FLAGS arguments change the behavior of the compiled regular expression.  The following flags may be supplied:

     regexp/icase
          Consider uppercase and lowercase letters to be the same when matching.

     regexp/newline
          If a newline appears in the target string, then permit the ^ and $ operators to match immediately after or immediately before the newline, respectively.  Also, the . and [^...] operators will never match a newline character.  The intent of this flag is to treat the target string as a buffer containing many lines of text, and the regular expression as a pattern that may match a single one of those lines.

     regexp/basic
          Compile a basic (``obsolete'') regexp instead of the extended (``modern'') regexps that are the default.  Basic regexps do not consider |, + or ? to be special characters, and require the {...} and (...) metacharacters to be backslash-escaped (see Backslash Escapes).  There are several other differences between basic and extended regular expressions, but these are the most significant.

     regexp/extended
          Compile an extended regular expression rather than a basic regexp.  This is the default behavior; this flag will not usually be needed.  If a call to make-regexp includes both regexp/basic and regexp/extended flags, the one which comes last will override the earlier one.

regexp-exec
 -- Scheme Procedure: regexp-exec rx str [start [flags]]
     Match the compiled regular expression RX against str.  If the optional integer START argument is provided, begin matching from that position in the string. Return a match structure describing the results of the match, or #f if no match could be found.

     The FLAGS arguments change the matching behavior. The following flags may be supplied:

     regexp/notbol
          Operator ^ always fails (unless regexp/newline is used).  Use this when the beginning of the string should not be considered the beginning of a line.

     regexp/noteol
          Operator $ always fails (unless regexp/newline is used).  Use this when the end of the string should not be considered the end of a line.