Ross
I've pushed a new branch, tc-arrows, for the new typechecking of arrows, based on the discussion we had last week.
It all compiles, but won't work because I have done nothing to the desugaring.
It uses our new representation with (env, nested-tuple-with-unit-at-end)
rather than (nested-tuple-with-env-at-the-end), so desugaring needs significant attention.
Would you like to work on the desugarer? I'm out of my depth, but happy to advise.
Thanks
Simon
| -----Original Message-----
| From: ghc-commits-bounces@haskell.org [mailto:ghc-commits-
| bounces@haskell.org] On Behalf Of Simon Peyton Jones
| Sent: 14 February 2013 16:08
| To: ghc-commits@haskell.org
| Subject: [commit: ghc] tc-arrows: Rearrange the typechecking of arrows,
| especially arrow "forms" (49badc9)
|
| Repository : ssh://darcs.haskell.org//srv/darcs/ghc
|
| On branch : tc-arrows
|
| http://hackage.haskell.org/trac/ghc/changeset/49badc91c52fc1f65a3ff5bfb3
| edaecbd617de61
|
| >---------------------------------------------------------------
|
| commit 49badc91c52fc1f65a3ff5bfb3edaecbd617de61
| Author: Simon Peyton Jones
| Date: Thu Feb 14 15:25:23 2013 +0000
|
| Rearrange the typechecking of arrows, especially arrow "forms"
|
| The typechecking of arrow forms (in GHC 7.6) is known to be bogus,
| because it marches down tuple types that may not yet be fully worked
| out, depending on when constraint solving happens. Moreover,
| coercions are generated and simply discarded. The fact that it
| works
| at all is a miracle.
|
| This refactoring is based on a conversation with Ross, where we
| rearranged the typing of the argument stack, so that the arrows
| have the form
| a (env, (arg1, (arg2, ...(argn, ())))) res
| rather than
| a (arg1, (arg2, ...(argn, env))) res
| as it was before.
|
| This is vastly simpler to typecheck; just look at the beautiful,
| simple type checking of arrow forms now!
|
| We need a new HsCmdCast to capture the coercions generated from
| the argument stack.
|
| Current state of play:
| * syntax done
| * renamer done
| * typechecker done
| * desugarer NOT DONE
|
| So nothing will work yet, hence on a branch
|
| compiler/deSugar/Coverage.lhs | 3 +
| compiler/deSugar/DsArrows.lhs | 6 +-
| compiler/hsSyn/HsExpr.lhs | 13 ++-
| compiler/hsSyn/HsUtils.lhs | 7 +-
| compiler/parser/Parser.y.pp | 4 +-
| compiler/parser/RdrHsSyn.lhs | 4 +-
| compiler/rename/RnExpr.lhs | 4 +-
| compiler/rename/RnTypes.lhs | 2 +-
| compiler/typecheck/TcArrows.lhs | 270 ++++++++++++++++++--------------
| -------
| compiler/typecheck/TcHsSyn.lhs | 6 +-
| 10 files changed, 156 insertions(+), 163 deletions(-)
|
|
| Diff suppressed because of size. To see it, use:
|
| git show 49badc91c52fc1f65a3ff5bfb3edaecbd617de61
|
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