(->) 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 |
|
| Differential revisions |
|
| BlockedBy |
|
| Related |
|
| Blocking |
|
| CC |
|
| Operating system |
|
| Architecture |
|
