[GHC] #8678: Derivin `Functor` complains about existential type
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Thu Jan 23 22:41:50 UTC 2014
#8678: Derivin `Functor` complains about existential type
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Reporter: heisenbug | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 7.7
Resolution: | Keywords:
Operating System: Unknown/Multiple | Architecture: Unknown/Multiple
Type of failure: None/Unknown | Difficulty: Unknown
Test Case: | Blocked By:
Blocking: | Related Tickets:
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Comment (by monoidal):
My guess is that the type of `Standard` is rewritten to `m ~ S n => a ->
NonStandard m a` (which is existential in `n`). Simpler test case: `data A
t a where A :: A Int a deriving Functor`.
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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8678#comment:3>
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