Re: [GHC] #7224: Polymorphic kind annotations on type classes don't always work as expected
#7224: Polymorphic kind annotations on type classes don't always work as expected +--- Reporter: slindley | Owner: Type: bug| Status: closed Priority: normal | Milestone: Component: Compiler (Type checker)|Version: 7.6.1-rc1 Resolution: fixed | Keywords: kind polymorphism Os: Unknown/Multiple | Architecture: Unknown/Multiple Failure: GHC rejects valid program | Difficulty: Unknown Testcase: polykinds/T7224| Blockedby: Blocking: |Related: +--- Changes (by igloo): * status: merge = closed * resolution: = fixed Comment: Merged as c4aa0165bb8eb4b65d8c1299fdff279e1f97bbb4 -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/7224#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler ___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
Re: [GHC] #7224: Polymorphic kind annotations on type classes don't always work as expected
#7224: Polymorphic kind annotations on type classes don't always work as
expected
+---
Reporter: slindley | Owner:
Type: bug | Status: merge
Priority: normal | Milestone:
Component: Compiler (Type checker) | Version: 7.6.1-rc1
Keywords: kind polymorphism| Os: Unknown/Multiple
Architecture: Unknown/Multiple | Failure: GHC rejects valid
program
Difficulty: Unknown |Testcase: polykinds/T7224
Blockedby: |Blocking:
Related: |
+---
Changes (by simonpj):
* status: new = merge
* difficulty: = Unknown
* testcase: = polykinds/T7224
Comment:
Thanks for the report. The declaration of {{{PMonad'}}} is bogus becuase
you are using a ''kind'' variable `i` in a ''type'', the type of
{{{ret'}}}. Now GHC says
{{{
T7224.hs:10:19:
Kind variable `i' used as a type
In the type `a - m i i a'
In the class declaration for PMonad'
}}}
Merge to 7.6 branh.
--
Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/7224#comment:3
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Re: [GHC] #7224: Polymorphic kind annotations on type classes don't always work as expected
#7224: Polymorphic kind annotations on type classes don't always work as expected +--- Reporter: slindley | Owner: Type: bug | Status: merge Priority: normal | Milestone: Component: Compiler (Type checker) | Version: 7.6.1-rc1 Keywords: kind polymorphism| Os: Unknown/Multiple Architecture: Unknown/Multiple | Failure: GHC rejects valid program Difficulty: Unknown |Testcase: polykinds/T7224 Blockedby: |Blocking: Related: | +--- Comment(by slindley): Ah yes. Kind variables bound at the top level of a type class definition are in scope for the rest of the class definition. I guess (if the GHC type system was suitably adapted) it might actually be useful to allow kind variables in types. -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/7224#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler ___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
Re: [GHC] #7224: Polymorphic kind annotations on type classes don't always work as expected
#7224: Polymorphic kind annotations on type classes don't always work as
expected
---+
Reporter: slindley | Owner:
Type: bug| Status: new
Priority: normal | Component: Compiler (Type
checker)
Version: 7.6.1-rc1 | Keywords: kind polymorphism
Os: Unknown/Multiple | Architecture: Unknown/Multiple
Failure: GHC rejects valid program | Testcase:
Blockedby: | Blocking:
Related: |
---+
Comment(by simonpj@…):
commit 77b63e74454170bd658c6773b9d5c172920d5cc5
{{{
Author: Simon Peyton Jones simo...@microsoft.com
Date: Mon Sep 10 13:13:24 2012 +0100
Two fixes to kind unification
* Don't unify a kind signature-variable with non-tyvar kind
* Don't allow a kind variable to appear in a type
(Trac #7224)
compiler/typecheck/TcHsType.lhs |9 +++--
compiler/typecheck/TcUnify.lhs | 20 ++--
2 files changed, 21 insertions(+), 8 deletions(-)
}}}
--
Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/7224#comment:2
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Re: [GHC] #7224: Polymorphic kind annotations on type classes don't always work as expected
#7224: Polymorphic kind annotations on type classes don't always work as
expected
---+
Reporter: slindley | Owner:
Type: bug| Status: new
Priority: normal | Component: Compiler (Type
checker)
Version: 7.6.1-rc1 | Keywords: kind polymorphism
Os: Unknown/Multiple | Architecture: Unknown/Multiple
Failure: GHC rejects valid program | Testcase:
Blockedby: | Blocking:
Related: |
---+
Comment(by slindley):
If I'd actually switched on PolyKinds in ghci as well as the source file,
then I'd have got:
{{{
*Main :t ret
ret :: PMonad k m = a - m i i a
*Main :t ret'
ret' :: PMonad' m = a - m BOX BOX a
}}}
(The mysterious * disappears if {{{PolyKinds}}} is enabled.)
--
Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/7224#comment:1
GHC http://www.haskell.org/ghc/
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[GHC] #7224: Polymorphic kind annotations on type classes don't always work as expected
#7224: Polymorphic kind annotations on type classes don't always work as
expected
---+
Reporter: slindley | Owner:
Type: bug| Status: new
Priority: normal | Component: Compiler (Type
checker)
Version: 7.6.1-rc1 | Keywords: kind polymorphism
Os: Unknown/Multiple | Architecture: Unknown/Multiple
Failure: GHC rejects valid program | Testcase:
Blockedby: | Blocking:
Related: |
---+
Consider the following code for defining Atkey-style parameterised monads:
{{{
{-# LANGUAGE
PolyKinds
#-}
class PMonad m where
ret :: a - m i i a
bind :: m i j a - (a - m j k b) - m i k b
class PMonad' (m :: i - i - * - *) where
ret' :: a - m i i a
bind' :: m i j a - (a - m j k b) - m i k b
}}}
The following types are inferred for {{{ret}}} and {{{ret'}}}:
{{{
*Main :t ret
ret :: PMonad * m = a - m i i a
*Main :t ret'
ret' :: PMonad' m = a - m BOX BOX a
}}}
But {{{ret'}}} should have the former type.
--
Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/7224
GHC http://www.haskell.org/ghc/
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