#6020: "Couldn't match kind" with free type variables and PolyKinds
---------------------------------------+------------------------------------
Reporter: atnnn | Owner:
Type: feature request | Status: new
Priority: normal | Component: Compiler
Version: 7.5 | Keywords:
Os: Unknown/Multiple | Architecture: Unknown/Multiple
Failure: GHC rejects valid program | Testcase:
Blockedby: | Blocking:
Related: |
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Comment(by atnnn):
Pinning the kind makes the instance work:
{{{
instance (Id x y, Id y z) => Test x (z :: Bool)
}}}
But using kind variables doesn't:
{{{
instance (Id x (y :: k), Id y z) => Test x (z :: k)
}}}
{{{
Not in scope: type variable `k'
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/6020#comment:1>
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