#6002: GHC 7.4+ thinks class instance is incoherent, 7.0.4 disagrees
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Reporter: heisenbug | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 7.4.1
Keywords: | Os: Unknown/Multiple
Architecture: Unknown/Multiple | Failure: GHC rejects valid program
Difficulty: Unknown | Testcase:
Blockedby: | Blocking:
Related: |
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Comment(by heisenbug):
I tried `IncoherentInstances` but the error message changed instead of
disappearing.
I ask myself, how did this work in 7.0.4? Are we checking constraints more
aggressively recently?
Also I have a user-defined kinds version here, maybe the inference logic
would be simpler when no phantom types are involved?
http://omega.googlecode.com/svn/mosaic/TypeMachinery.kinds.lhs
Thanks for looking into this!
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/6002#comment:2>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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