Ken Friis Larsen, 2000

Note about the PM prototype
---------------------------

* Getting started.
  Compile the source with the command 
    mosmlc -toplevel Parsercomb-sig.sml Parsercomb.sml PMBasic.sml\
                     PMCompile.sml ArgParse-sig.sml ArgParse.sml\
                     mosmlpm.sml -o mosmlpm
  Now from the toplevel invoke the function 
  PMCompile.compile "sources.pm"

  (app load ["Mosml", "PMCompile"]; 
   FileSys.chDir "/home/kfl/programming/ml/mlkit.mosml/kit/src";
   PMCompile.compile "sources.pm";
   PMCompile.link ["-o moskit "] "sources.pm";)


* Everything managed by pm is compiled with the command
	mosmlc -c -toplevel context1 ... contextM file1 ... fileN
  where file1 to fileN are .sml files and context1 to contextM are .ui
  files.  (This is the general case in compileBodyOpt, in compileBody
  N=1.  I thought compileBodyOpt would gain some speed but that does
  not seem to be the case)

* PMCompile.compilePM returns the context obtained from a pmfile
  data structure.

* All filenames are transformed to be fullpath'ed

* 5/5 - 2000: Changes made to the kit so as it can be compiled with mosml 1.99
  + Made a mosmlhacks.pm file.  The only thing in there now is the
    Word32 hack.
  + Added Compiler/compilerx86.pm
  + Used mosmlhack.pm in Compiler/compilerx86.pm
  + Changed sources.pm to use Compiler/compilerx86.pm and 
    Compiler/Backend/X86/ExecutionX86.sml
  + Changes from Martin in basislib/Initial.sml
  + Changed 
	    val garbage_collection = ref true
    to
	    val garbage_collection = ref false
    in src/Common/Flags.sml
  + Changed `status' to `~1' on line 128 in
    Manager/ManagerObjects.sml
  + Renamed Edlib/List.sml Edlib/edList.sml
    and Edlib/ListPair.sml Edlib/edListPair.sml
  + Renamed Parsing/Topdec.grm.sig to Parsing/Topdec.grm-sig.sml (also
    in Common/common.pm) 
  + Renamed Common/BasicIO.sml Common/commonBasicIO.sml
  + Corrected a sharing spec bug (not decteded by sml/nj) in
    Compiler/Backend/X86/CodeGenX86.sml

  Many of these errors can be boiled down to:
  + We need a way to rename a compilation unit


* After I have implemented the findFiles functions, I realize that the
  Right Way to handle the pm files is to build a graph representation
  from them.  This will also make it easy to check that the pm files
  don't contains cycles (we just check that the graph is a DAG).

* Locals might be handled wrong when things are linked, because
  compilation unit renaming is not supported.

* 3/4- 2000: Smarter recompilation implemented.  Broke compileBodyOpt
  doing this, but who cares.
  BUG: .pm files are not considered in the uptodate check.

* 4/5 - 2000: Even smarter recompilation scheme implemented thanks to
  Martin.  Now .ui is checked for equality.

TODO ( - : not implemented, + : implemented, * : droped ) 
  - Implement compilation unit renaming when mosmlc supports it
  - Figure out how to handle .sig files
  - Reimplement using graph data structure
  + Implement smart recompilation.  That is, don't recompile if the
    context and the .u? files are up to date. (This might also be
    easier, if we had a graph.  But on the other hand Holmake seems to
    do fine without one)
  - Make everything robust wrt missing files, syntax errors in pm
    files, etc.
  - Testing, testing, testing.  Lots of test done in the interactive
    environment, and the kit seems to be a good test case but still it
    would be nice with some systematic test files so as we can track
    when and how we break pm.