#6049: Kind variable generalization error in GADTs
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Reporter: goldfire | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler (Type checker) | Version: 7.5
Keywords: PolyKinds | Os: Unknown/Multiple
Architecture: Unknown/Multiple | Failure: GHC rejects valid
program
Difficulty: Unknown | Testcase:
Blockedby: | Blocking:
Related: |
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Comment(by simonpj@…):
commit c91172004f2a5a6bf201b418c32c2d640ee34049
{{{
Author: Simon Peyton Jones <[email protected]>
Date: Thu Jun 7 12:09:22 2012 +0100
Support polymorphic kind recursion
This is (I hope) the last major patch for kind polymorphism.
The big new feature is polymorphic kind recursion when you
supply a complete kind signature for a type constructor.
(I've documented it in the user manual too.)
This fixes Trac #6137, #6093, #6049.
The patch also makes type/data families less polymorphic by default.
data family T a
now defaults to T :: * -> *
If you want T :: forall k. k -> *, use
data family T (a :: k)
This defaulting to * is done whenever there is a
"complete, user-specified kind signature", something that is
carefully defined in the user manual.
Hurrah!
compiler/typecheck/TcBinds.lhs | 3 +-
compiler/typecheck/TcClassDcl.lhs | 49 --------
compiler/typecheck/TcHsType.lhs | 50 ++++++--
compiler/typecheck/TcInstDcls.lhs | 106 +++++------------
compiler/typecheck/TcRnDriver.lhs | 66 ++++++++---
compiler/typecheck/TcRnTypes.lhs | 31 ++----
compiler/typecheck/TcSplice.lhs | 3 +-
compiler/typecheck/TcTyClsDecls.lhs | 204
++++++++++++++++++-------------
docs/users_guide/flags.xml | 5 +-
docs/users_guide/glasgow_exts.xml | 228
++++++++++++++++++++++-------------
10 files changed, 400 insertions(+), 345 deletions(-)
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/6049#comment:5>
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