External Core typechecker - improve handling of coercions

[ghc-hetmet.git] / utils / ext-core / README

diff --git a/utils/ext-core/README b/utils/ext-core/README
index 6b8168d..4fb16ff 100644 (file)
--- a/utils/ext-core/README
+++ b/utils/ext-core/README
@@ -2,10 +2,50 @@ A set of example programs for handling external core format.
 
 In particular, typechecker and interpreter give a precise semantics.
 
-All can be built using, e.g.,
+To build, run "make".
+---------------------
+tjc April 2008:
 
-happy -o Parser.hs Parser.y
-ghc --make -package text -fglasgow-exts  -o Driver Driver.hs
+==== Notes ====
+
+The checker should work on most programs. Bugs I'm aware of:
+1. There's some business I don't quite understand involving
+   coercions and subkinding (for details, see:
+   http://www.haskell.org/pipermail/cvs-ghc/2008-April/041949.html)
+   This shows up when typechecking a few of the library modules.
+   
+2. There's some weirdness involving funny character literals. This can
+   be fixed by writing a new lexer for chars rather than using Parsec's
+   built-in charLiteral lexer. But I haven't done that.
+
+3. When typechecking the ghc-prim:GHC.PrimopWrappers library module,
+   some declarations seem to have the wrong type signature (due to 
+   confusion between (forall (t::*) ...) and (forall (t::?) ...).)
+   This may be a GHC bug.
+
+Typechecking all the GHC libraries eats about a gig of heap and takes a
+long time. I blame Parsec. (Someone who was bored, or understood happy
+better than I do, could update the old happy parser, which is still in the
+repo.)
+
+The interpreter is not working yet.
+
+==== Building ====
+
+To run the checker and interpreter, you need to generate External Core
+for all the base, integer and ghc-prim libraries. This can be done by
+adding "-fext-core" to the GhcLibHcOpts in your build.mk file, then
+running "make" under libraries/.
+
+Then you need to edit Driver.hs and change "baseDir" to point to your GHC
+libraries directory.
+
+Once you've done that:
+1. make prims (to generate the primops file)
+2. make
+3. make nofibtest (to run the parser/checker on all nofib programs...
+   for example.)
+
+Tested with GHC 6.8.2. I make no claims of portability.
 
-Most recently tested with GHC 6.8.1. I make no claims of portability. --tjc