(->) used prefix doesn't work with unboxed kinds
This fails, but should succeed
f :: (->) Int# Int#
f x = x
-- Here's the comment from TypeRep:
--
-- funTyCon = mkFunTyCon funTyConName
-- (mkArrowKinds [liftedTypeKind,
liftedTypeKind]
-- liftedTypeKind)
-- You might think that (->) should have type (? -> ? ->
*), and you'd be right
-- But if we do that we get kind errors when saying
-- instance Control.Arrow (->)
-- becuase the expected kind is (*->*->*). The trouble
is that the
-- expected/actual stuff in the unifier does not go
contra-variant, whereas
-- the kind sub-typing does. Sigh. It really only
matters if you use (->) in
-- a prefix way, thus: (->) Int# Int#. And this is
unusual.
Trac metadata
Trac field |
Value |
Version |
None |
Type |
Bug |
TypeOfFailure |
OtherFailure |
Priority |
normal |
Resolution |
ResolvedFixed |
Component |
Compiler (Type checker) |
Test case |
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Differential revisions |
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BlockedBy |
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Related |
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Blocking |
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CC |
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Operating system |
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Architecture |
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