Kindness of strangers (or strangeness of Kinds)
anthony_clayden at clear.net.nz
Tue Jun 12 08:26:46 CEST 2012
Edward Kmett <ekmett <at> gmail.com> writes:
> On Mon, Jun 11, 2012 at 9:58 PM, AntC <anthony_clayden <at> clear.net.nz>
>> [snip ...]
>> Could we have :k (->) :: OpenKind -> * -> * -- why not?
> I don't quite understand why you would want arbitrary kinded arguments, but
only in negative position.
Thanks Edward, oops I've used the wrong terminology, sorry for the confusion.
I didn't mean OpenKind but AnyKind. I put that only in a negative position
more to sharpen the question, but also because I assumed the result from (->)
would have to be grounded in Kind *; and then at least one of its arguments
would also have to be grounded in Kind *.
I think perhaps(?) more PolyKindness is on the horizon:
http://hackage.haskell.org/trac/ghc/wiki/GhcKinds (section on GADKs, and sub-
pages on KindPolymorphism and ExplicitTypeApplication). I guess GHC is getting
there by small steps, and doesn't yet have powerful enough Kind refinement nor
Kind equality constraints, nor interleaving of Type and Kind inference.
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