#4917: ghc7 does not equate type synonyms under RankNTypes
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Reporter: kyagrd | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 7.0.1 | Keywords:
Testcase: | Blockedby:
Os: Linux | Blocking:
Architecture: x86_64 (amd64) | Failure: GHC rejects valid program
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See the source at
http://hpaste.org/43297/ghc7_problem_with_rankntypes_a
It works on ghc6 but not on ghc 7
The type error message is
ghc7rankn.hs:23:20:
Couldn't match expected type `forall a'1.
x a'1 -> Const (Const b a') a'1'
with actual type `forall a'1. x1 a'1 -> Const b a'1'
Expected type: (forall a'1. x a'1 -> Const (Const b a') a'1)
-> f x a
-> Const (Const b a') a
Actual type: (forall a'1. x1 a'1 -> Const b a'1)
-> f1 x1 a1
-> Const b a1
In the first argument of `mcata', namely `f'
In the first argument of `f', namely `(mcata f)'
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4917>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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