[MLton] Re: exene example

[Matthew Fluet]

> Type inference issues....
>
> For whatever reason we had many problems with infering option types in this 
> exene build.

I think many of your problems arise from an inappropriate use of .mlb 
files.  For example, you have:

portExene/eXene/examples/triangle/sources.mlb:

local
  /homes/lziarek/stabalize/code/mlton/basis-library/basis.mlb
  /homes/lziarek/stabalize/code/mlton/basis-library/mlton.mlb
  /homes/lziarek/stabalize/code/mlton/lib/cml/cml-lib/cml-lib.mlb
  /homes/lziarek/stabalize/code/mlton/lib/cml/cml.mlb
   ../../sources.mlb
in
   icon-bitmap.sml
   mltonTri.sml
end

This will almost certainly cause problems, because cml/cml.mlb (whether it 
is at /homes/lziarek/stabalize/code/mlton/lib/ or at $(SML_LIB)) has:

ann
    "forceUsed"
in
    core-cml/core-cml.mlb
    cml-lib/cml-lib.mlb
end

and cml/cml-lib/core-cml/core-cml.mlb has:

ann
    "sequenceNonUnit warn"
    "nonexhaustiveMatch warn" "redundantMatch warn"
    "warnUnused true"
in
    local
       $(SML_LIB)/basis/basis.mlb
       $(SML_LIB)/basis/mlton.mlb
...


What is happening is that you are compiling two separate copies of the 
Basis Library: one from /homes/lziarek/stabalize/code/mlton/basis-library 
and one from $(SML_LIB)/basis.  (Most likely $(SML_LIB) is set to 
/usr/share/mlton/sml, but it might also be set to something like 
/home/fluet/mlton/mlton.svn.HEAD/build/lib/sml if you are invoking a local 
build.)

This explains your "option" problem, because the "option" types defined in 
the two copies of the Basis Library are different.  (In particular, option 
is defined directly as "datatype 'a option = NONE | SOME of 'a", and hence 
is generative.)

I suspect that this is also the cause of some of your other problems, but 
I'll investigate a little more.


My suggestion, if you need to modify the Basis Library and CML Library, 
would be to isolate your work in a directory:

/homes/lziarek/stabalize/code/mlton.eXene

with a full check-out of the MLton source tree.  Make your modifications 
to the Basis Library and the CML Library in

/homes/lziarek/stabalize/code/mlton.eXene/basis-library
/homes/lziarek/stabalize/code/mlton.eXene/lib/cml-lib

respectively.  Build MLton (i.e., make all) in your mlton.eXene directory.

Update your eXene port to use $(SML_LIB)/basis and $(SML_LIB)/cml-lib 
instead of absolute paths.  When you want to compile and test an eXene 
example, make sure that you invoke:
   /homes/lziarek/stabalize/code/mlton.eXene/build/bin/mlton
That will ensure that you are compiling with $(SML_LIB) pointing to your 
modified libraries.

If you need to make further modifications to the Basis Library or the CML 
Library, you will need to do "make basis libraries" afterward to propagate 
your changes to the build/lib/sml directory, which is where $(SML_LIB) 
will be pointing.  That will be much quicker than "make all".