Streams and Reading
*******************

 -- Function: MAKE-ECHO-STREAM (input-stream output-stream)
     Package:LISP

     Returns a bidirectional stream which gets its input from INPUT-STREAM and sends its output to OUTPUT-STREAM.  In addition, all input is echoed to OUTPUT-STREAM.

 -- Variable: *READTABLE*
     Package:LISP The current readtable.

 -- Function: LOAD (filename
     &key (verbose *load-verbose*) (print nil) (if-does-not-exist :error)) Package:LISP

     Loads the file named by FILENAME into GCL.

 -- Function: OPEN (filename &key (direction :input) (element-type 'string-char)
     (if-exists :error) (if-does-not-exist :error)) Package:LISP

     Opens the file specified by FILENAME, which may be a string, a pathname, or a stream.  Returns a stream for the open file. DIRECTION is  :INPUT, :OUTPUT, :IO or :PROBE. ELEMENT-TYPE is  STRING-CHAR, (UNSIGNED-BYTE n), UNSIGNED-BYTE, (SIGNED-BYTE n), SIGNED-BYTE, CHARACTER, BIT, (MOD n), or :DEFAULT. IF-EXISTS is :ERROR, :NEW-VERSION, :RENAME, :RENAME-AND-DELETE, :OVERWRITE, :APPEND, :SUPERSEDE, or NIL. IF-DOES-NOT-EXIST is  :ERROR, :CREATE, or NIL.

 -- Variable: *PRINT-BASE*
     Package:LISP The radix in which the GCL printer prints integers and rationals. The value must be an integer from 2 to 36, inclusive.

 -- Function: MAKE-STRING-INPUT-STREAM (string &optional (start 0) (end (length string)))
     Package:LISP

     Returns an input stream which will supply the characters of String between Start and End in order.

 -- Function: PPRINT (object &optional (stream *standard-output*))
     Package:LISP

     Pretty-prints OBJECT.  Returns OBJECT.  Equivalent to (WRITE :STREAM STREAM :PRETTY T) The SI:PRETTY-PRINT-FORMAT property N (which must be a non-negative integer) of a symbol SYMBOL controls the pretty-printing of form (SYMBOL f1 ... fN fN+1 ... fM) in such a way that the subforms fN+1, ..., fM are regarded as the 'body' of the entire form.  For instance, the property value of 2 is initially given to the symbol DO.

 -- Variable: *READ-DEFAULT-FLOAT-FORMAT*
     Package:LISP The floating-point format the GCL reader uses when reading floating-point numbers that have no exponent marker or have e or E for an exponent marker. Must be one of SHORT-FLOAT, SINGLE-FLOAT, DOUBLE-FLOAT, and LONG-FLOAT.

 -- Function: READ-PRESERVING-WHITESPACE (&optional (stream *standard-input*) (eof-error-p t) (eof-value nil)
     (recursive-p nil)) Package:LISP

     Reads an object from STREAM, preserving the whitespace that followed the object.

 -- Function: STREAMP (x)
     Package:LISP

     Returns T if X is a stream object; NIL otherwise.

 -- Function: SET-DISPATCH-MACRO-CHARACTER (disp-char sub-char function &optional (readtable *readtable*))
     Package:LISP

     Causes FUNCTION to be called when the DISP-CHAR followed by SUB-CHAR is read.

 -- Macro: WITH-OUTPUT-TO-STRING
     Package:LISP

     Syntax:

          (with-output-to-string (var [string]) {decl}* {form}*)

     Binds VAR to a string output stream that puts characters into STRING, which defaults to a new string.  The stream is automatically closed on exit and the string is returned.

 -- Function: FILE-LENGTH (file-stream)
     Package:LISP

     Returns the length of the specified file stream.

 -- Variable: *PRINT-CASE*
     Package:LISP The case in which the GCL printer should print ordinary symbols. The value must be one of the keywords :UPCASE, :DOWNCASE, and :CAPITALIZE.

 -- Function: PRINT (object &optional (stream *standard-output*))
     Package:LISP

     Outputs a newline character, and then prints OBJECT in the mostly readable representation.  Returns OBJECT.  Equivalent to (PROGN (TERPRI STREAM) (WRITE OBJECT :STREAM STREAM :ESCAPE T)).

 -- Function: SET-MACRO-CHARACTER (char function
     &optional (non-terminating-p nil) (readtable *readtable*)) Package:LISP

     Causes CHAR to be a macro character that, when seen by READ, causes FUNCTION to be called.

 -- Function: FORCE-OUTPUT (&optional (stream *standard-output*))
     Package:LISP

     Attempts to force any buffered output to be sent.

 -- Variable: *PRINT-ARRAY*
     Package:LISP Whether the GCL printer should print array elements.

 -- Function: STREAM-ELEMENT-TYPE (stream)
     Package:LISP

     Returns a type specifier for the kind of object returned by STREAM.

 -- Function: WRITE-BYTE (integer stream)
     Package:LISP

     Outputs INTEGER to the binary stream STREAM.  Returns INTEGER.

 -- Function: MAKE-CONCATENATED-STREAM (&rest streams)
     Package:LISP

     Returns a stream which takes its input from each of the STREAMs in turn, going on to the next at end of stream.

 -- Function: PRIN1 (object &optional (stream *standard-output*))
     Package:LISP

     Prints OBJECT in the mostly readable representation.  Returns OBJECT. Equivalent to (WRITE OBJECT :STREAM STREAM :ESCAPE T).

 -- Function: PRINC (object &optional (stream *standard-output*))
     Package:LISP

     Prints OBJECT without escape characters.  Returns OBJECT.  Equivalent to (WRITE OBJECT :STREAM STREAM :ESCAPE NIL).

 -- Function: CLEAR-OUTPUT (&optional (stream *standard-output*))
     Package:LISP

     Clears the output stream STREAM.

 -- Function: TERPRI (&optional (stream *standard-output*))
     Package:LISP

     Outputs a newline character.

 -- Function: FINISH-OUTPUT (&optional (stream *standard-output*))
     Package:LISP

     Attempts to ensure that all output sent to STREAM has reached its destination, and only then returns.

 -- Macro: WITH-OPEN-FILE
     Package:LISP

     Syntax:

          (with-open-file (stream filename {options}*) {decl}* {form}*)

     Opens the file whose name is FILENAME, using OPTIONs, and binds the variable STREAM to a stream to/from the file.  Then evaluates FORMs as a PROGN. The file is automatically closed on exit.

 -- Special Form: DO
     Package:LISP

     Syntax:

          (do ({(var [init [step]])}*) (endtest {result}*)
                    {decl}* {tag | statement}*)

     Creates a NIL block, binds each VAR to the value of the corresponding INIT, and then executes STATEMENTs repeatedly until ENDTEST is satisfied.  After each iteration, assigns to each VAR the value of the corresponding STEP.  When ENDTEST is satisfied, evaluates RESULTs as a PROGN and returns the value(s) of the last RESULT (or NIL if no RESULTs are supplied).  Performs variable bindings and assignments all at once, just like LET and PSETQ do.

 -- Function: READ-FROM-STRING (string &optional (eof-error-p t) (eof-value nil)
     &key (start 0) (end (length string)) (preserve-whitespace nil)) Package:LISP

     Reads an object from STRING.

 -- Function: WRITE-STRING (string &optional (stream *standard-output*)
     &key (start 0) (end (length string))) Package:LISP

     Outputs STRING and returns it.

 -- Variable: *PRINT-LEVEL*
     Package:LISP How many levels deep the GCL printer should print.  Unlimited if NIL.

 -- Variable: *PRINT-RADIX*
     Package:LISP Whether the GCL printer should print the radix indicator when printing integers and rationals.

 -- Function: Y-OR-N-P (&optional (format-string nil) &rest args)
     Package:LISP

     Asks the user a question whose answer is either 'Y' or 'N'.  If FORMAT-STRING is non-NIL, then FRESH-LINE operation is performed, a message is printed as if FORMAT-STRING and ARGs were given to FORMAT, and then a prompt "(Y or N)" is printed.  Otherwise, no prompt will appear.

 -- Function: MAKE-BROADCAST-STREAM (&rest streams)
     Package:LISP

     Returns an output stream which sends its output to all of the given streams.

 -- Function: READ-CHAR (&optional (stream *standard-input*) (eof-error-p t)
     (eof-value nil) (recursive-p nil)) Package:LISP

     Reads a character from STREAM.

 -- Function: PEEK-CHAR (&optional (peek-type nil) (stream *standard-input*) (eof-error-p t)
     (eof-value nil) (recursive-p nil)) Package:LISP

     Peeks at the next character in the input stream STREAM.

 -- Function: OUTPUT-STREAM-P (stream)
     Package:LISP

     Returns non-nil if STREAM can handle output operations; NIL otherwise.

 -- Variable: *QUERY-IO*
     Package:LISP The query I/O stream.

 -- Variable: *READ-BASE*
     Package:LISP The radix that the GCL reader reads numbers in.

 -- Macro: WITH-OPEN-STREAM
     Package:LISP

     Syntax:

          (with-open-stream (var stream) {decl}* {form}*)

     Evaluates FORMs as a PROGN with VAR bound to the value of STREAM.  The stream is automatically closed on exit.

 -- Macro: WITH-INPUT-FROM-STRING
     Package:LISP

     Syntax:

          (with-input-from-string (var string {keyword value}*) {decl}*
          {form}*)

     Binds VAR to an input stream that returns characters from STRING and evaluates the FORMs.  The stream is automatically closed on exit.  Allowed keywords are :INDEX, :START, and :END.

 -- Function: CLEAR-INPUT (&optional (stream *standard-input*))
     Package:LISP Clears the input stream STREAM.

 -- Variable: *TERMINAL-IO*
     Package:LISP The terminal I/O stream.

 -- Function: LISTEN (&optional (stream *standard-input*))
     Package:LISP

     Returns T if a character is available on STREAM; NIL otherwise.  This function does not correctly work in some versions of GCL because of the lack of such mechanism in the underlying operating system.

 -- Function: MAKE-PATHNAME (&key (defaults (parse-namestring ""
     (pathname-host *default-pathname-defaults*))) (host (pathname-host defaults)) (device (pathname-device defaults)) (directory (pathname-directory defaults)) (name (pathname-name defaults)) (type (pathname-type defaults)) (version (pathname-version defaults))) Package:LISP

     Create a pathname from HOST, DEVICE, DIRECTORY, NAME, TYPE and VERSION.

 -- Function: PATHNAME-TYPE (pathname)
     Package:LISP

     Returns the type slot of PATHNAME.

 -- Variable: *PRINT-GENSYM*
     Package:LISP Whether the GCL printer should prefix symbols with no home package with "#:".

 -- Function: READ-LINE (&optional (stream *standard-input*) (eof-error-p t)
     (eof-value nil) (recursive-p nil)) Package:LISP

     Returns a line of text read from STREAM as a string, discarding the newline character.

     Note that when using line at a time input under unix, input forms will always be followed by a #\newline.   Thus if you do

     >(read-line) "" nil

     the empty string will be returned.  After lisp reads the (read-line) it then invokes (read-line).  This happens before it does anything else and so happens before the newline character immediately following (read-line) has been read.  Thus read-line immediately encounters a #\newline and so returns the empty string.  If there had been other characters before the #\newline it would have been different:

     >(read-line) how are you " how are you" nil

     If you want to throw away "" input, you can do that with the following:

     (sloop::sloop while (equal (setq input (read-line)) ""))

     You may also want to use character at a time input, but that makes input editing harder. nicolas% stty cbreak nicolas% gcl GCL (GNU Common Lisp)  Version(1.1.2) Mon Jan  9 12:58:22 MET 1995 Licensed under GNU Public Library License Contains Enhancements by W. Schelter

     >(let ((ifilename nil)) (format t "~%Input file name: ") (setq ifilename (read-line))) Input file name: /tmp/myfile "/tmp/myfile"

     >(bye)Bye.

 -- Function: WRITE-TO-STRING (object &key (escape *print-escape*) (radix *print-radix*)
     (base *print-base*) (circle *print-circle*) (pretty *print-pretty*) (level *print-level*) (length *print-length*) (case *print-case*) (array *print-array*) (gensym *print-gensym*)) Package:LISP

     Returns as a string the printed representation of OBJECT in the specified mode.  See the variable docs of *PRINT-...* for the mode.

 -- Function: PATHNAMEP (x)
     Package:LISP

     Returns T if X is a pathname object; NIL otherwise.

 -- Function: READTABLEP (x)
     Package:LISP

     Returns T if X is a readtable object; NIL otherwise.

 -- Function: READ (&optional (stream *standard-input*) (eof-error-p t) (eof-value nil)
     (recursivep nil)) Package:LISP

     Reads in the next object from STREAM.

 -- Function: NAMESTRING (pathname)
     Package:LISP

     Returns the full form of PATHNAME as a string.

 -- Function: UNREAD-CHAR (character &optional (stream *standard-input*))
     Package:LISP

     Puts CHARACTER back on the front of the input stream STREAM.

 -- Function: CLOSE (stream &key (abort nil))
     Package:LISP

     Closes STREAM.  A non-NIL value of :ABORT indicates an abnormal termination.

 -- Variable: *PRINT-LENGTH*
     Package:LISP How many elements the GCL printer should print at each level of nested data object.  Unlimited if NIL.

 -- Function: SET-SYNTAX-FROM-CHAR (to-char from-char
     &optional (to-readtable *readtable*) (from-readtable nil)) Package:LISP

     Makes the syntax of TO-CHAR in TO-READTABLE be the same as the syntax of FROM-CHAR in FROM-READTABLE.

 -- Function: INPUT-STREAM-P (stream)
     Package:LISP

     Returns non-NIL if STREAM can handle input operations; NIL otherwise.

 -- Function: PATHNAME (x)
     Package:LISP

     Turns X into a pathname.  X may be a string, symbol, stream, or pathname.

 -- Function: FILE-NAMESTRING (pathname)
     Package:LISP

     Returns the written representation of PATHNAME as a string.

 -- Function: MAKE-DISPATCH-MACRO-CHARACTER (char &optional (non-terminating-p nil) (readtable *readtable*))
     Package:LISP

     Causes the character CHAR to be a dispatching macro character in READTABLE.

 -- Variable: *STANDARD-OUTPUT*
     Package:LISP The default output stream used by the GCL printer.

 -- Function: MAKE-TWO-WAY-STREAM (input-stream output-stream)
     Package:LISP

     Returns a bidirectional stream which gets its input from INPUT-STREAM and sends its output to OUTPUT-STREAM.

 -- Variable: *PRINT-ESCAPE*
     Package:LISP Whether the GCL printer should put escape characters whenever appropriate.

 -- Function: COPY-READTABLE (&optional (from-readtable *readtable*) (to-readtable nil))
     Package:LISP

     Returns a copy of the readtable FROM-READTABLE.  If TO-READTABLE is non-NIL, then copies into TO-READTABLE.  Otherwise, creates a new readtable.

 -- Function: DIRECTORY-NAMESTRING (pathname)
     Package:LISP

     Returns the directory part of PATHNAME as a string.

 -- Function: TRUENAME (pathname)
     Package:LISP

     Returns the pathname for the actual file described by PATHNAME.

 -- Variable: *READ-SUPPRESS*
     Package:LISP When the value of this variable is NIL, the GCL reader operates normally. When it is non-NIL, then the reader parses input characters but much of what is read is not interpreted.

 -- Function: GET-DISPATCH-MACRO-CHARACTER (disp-char sub-char &optional (readtable *readtable*))
     Package:LISP

     Returns the macro-character function for SUB-CHAR under DISP-CHAR.

 -- Function: PATHNAME-DEVICE (pathname)
     Package:LISP

     Returns the device slot of PATHNAME.

 -- Function: READ-CHAR-NO-HANG (&optional (stream *standard-input*) (eof-error-p t)
     (eof-value nil) (recursive-p nil)) Package:LISP

     Returns the next character from STREAM if one is available; NIL otherwise.

 -- Function: FRESH-LINE (&optional (stream *standard-output*))
     Package:LISP

     Outputs a newline if it is not positioned at the beginning of a line.  Returns T if it output a newline; NIL otherwise.

 -- Function: WRITE-CHAR (char &optional (stream *standard-output*))
     Package:LISP

     Outputs CHAR and returns it.

 -- Function: PARSE-NAMESTRING (thing &optional host (defaults *default-pathname-defaults*)
     &key (start 0) (end (length thing)) (junk-allowed nil)) Package:LISP

     Parses a string representation of a pathname into a pathname.  HOST is ignored.

 -- Function: PATHNAME-DIRECTORY (pathname)
     Package:LISP

     Returns the directory slot of PATHNAME.

 -- Function: GET-MACRO-CHARACTER (char &optional (readtable *readtable*))
     Package:LISP

     Returns the function associated with CHAR and, as a second value, returns the non-terminating-p flag.

 -- Function: FORMAT (destination control-string &rest arguments)
     Package:LISP

     Provides various facilities for formatting output. DESTINATION controls where the result will go.  If DESTINATION is T, then the output is sent to the standard output stream.  If it is NIL, then the output is returned in a string as the value of the call.  Otherwise, DESTINATION must be a stream to which the output will be sent.

     CONTROL-STRING is a string to be output, possibly with embedded formatting directives, which are flagged with the escape character "~".  Directives generally expand into additional text to be output, usually consuming one or more of ARGUMENTs in the process.

     A few useful directives are:

     ~A, ~nA, ~n@A	Prints one argument as if by PRINC
     ~S, ~nS, ~n@S	Prints one argument as if by PRIN1
     ~D, ~B, ~O, ~X	Prints one integer in decimal, binary, octal, and hexa
     ~%		Does TERPRI
     ~&		Does FRESH-LINE

     where n is the minimal width of the field in which the object is printed. ~nA and ~nS put padding spaces on the right; ~n@A and ~n@S put on the left.

     ~R  is for printing numbers in various formats.

     ~nR   prints arg in radix n.
     ~R    prints arg as a cardinal english number: two
     ~:R   prints arg as an ordinal english number: third
     ~@R   prints arg as an a Roman Numeral: VII
     ~:@R   prints arg as an old Roman Numeral: IIII

     ~C prints a character. ~:C represents non printing characters by their pretty names,eg Space ~@C uses the #\ syntax to allow the reader to read it.

     ~F prints a floating point number arg. The full form is ~w,d,k,overflowchar,padcharF w represents the total width of the printed representation (variable if not present) d the number of fractional digits to display (format nil "~,2f" 10010.0314) --> "10010.03" k arg is multiplied by 10^k before printing it as a decimal number. overflowchar width w characters copies of the overflow character will be printed.   eg(format t "X>~5,2,,'?F<X" 100.034) --> X>?????<X padchar is the character to pad with (format t "X>~10,2,1,'?,'bF<X" 100.03417) -->X>bbb1000.34<X @ makes + sign print if the arg is positive

     ~@[print-if-true~] if arg is not nil, then it is retained as an arg for further printing, otherwise it is used up (format nil "~@[x = ~d~]~a" nil 'bil) --> "BIL" (format nil "~@[x = ~d ~]~a" 8) --> "x = 8 BIL"

 -- Function: PATHNAME-NAME (pathname)
     Package:LISP

     Returns the name slot of PATHNAME.

 -- Function: MAKE-STRING-OUTPUT-STREAM ()
     Package:LISP

     Returns an output stream which will accumulate all output given it for the benefit of the function GET-OUTPUT-STREAM-STRING.

 -- Function: MAKE-SYNONYM-STREAM (symbol)
     Package:LISP

     Returns a stream which performs its operations on the stream which is the value of the dynamic variable named by SYMBOL.

 -- Variable: *LOAD-VERBOSE*
     Package:LISP The default for the VERBOSE argument to LOAD.

 -- Variable: *PRINT-CIRCLE*
     Package:LISP Whether the GCL printer should take care of circular lists.

 -- Variable: *PRINT-PRETTY*
     Package:LISP Whether the GCL printer should pretty-print.  See the function doc of PPRINT for more information about pretty-printing.

 -- Function: FILE-WRITE-DATE (file)
     Package:LISP

     Returns the time at which the specified file is written, as an integer in universal time format.  FILE may be a string or a stream.

 -- Function: PRIN1-TO-STRING (object)
     Package:LISP

     Returns as a string the printed representation of OBJECT in the mostly readable representation. Equivalent to (WRITE-TO-STRING OBJECT :ESCAPE T).

 -- Function: MERGE-PATHNAMES (pathname
     &optional (defaults *default-pathname-defaults*) default-version) Package:LISP

     Fills in unspecified slots of PATHNAME from DEFAULTS.  DEFAULT-VERSION is ignored in GCL.

 -- Function: READ-BYTE (stream &optional (eof-error-p t) (eof-value nil))
     Package:LISP

     Reads the next byte from STREAM.

 -- Function: PRINC-TO-STRING (object)
     Package:LISP

     Returns as a string the printed representation of OBJECT without escape characters.  Equivalent to (WRITE-TO-STRING OBJECT :ESCAPE NIL).

 -- Variable: *STANDARD-INPUT*
     Package:LISP The default input stream used by the GCL reader.

 -- Function: PROBE-FILE (file)
     Package:LISP

     Returns the truename of file if the file exists. Returns NIL otherwise.

 -- Function: PATHNAME-VERSION (pathname)
     Package:LISP

     Returns the version slot of PATHNAME.

 -- Function: WRITE-LINE (string &optional (stream *standard-output*)
     &key (start 0) (end (length string))) Package:LISP

     Outputs STRING and then outputs a newline character.  Returns STRING.

 -- Function: WRITE (object &key (stream *standard-output*) (escape *print-escape*)
     (radix *print-radix*) (base *print-base*) (circle *print-circle*) (pretty *print-pretty*) (level *print-level*) (length *print-length*) (case *print-case*) (array *print-array*) (gensym *print-gensym*)) Package:LISP

     Prints OBJECT in the specified mode.  See the variable docs of *PRINT-...* for the mode.

 -- Function: GET-OUTPUT-STREAM-STRING (stream)
     Package:LISP

     Returns a string of all the characters sent to STREAM made by MAKE-STRING-OUTPUT-STREAM since the last call to this function.

 -- Function: READ-DELIMITED-LIST (char &optional (stream *standard-input*) (recursive-p nil))
     Package:LISP

     Reads objects from STREAM until the next character after an object's representation is CHAR.  Returns a list of the objects read.