Haskell Weird Kinds
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Published on 2010-06-13T23:15:08Z
Indexed on
2010/06/13
23:22 UTC
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haskell
When I was experimenting with Haskell kinds, and trying to get the kind of ->
, and this showed up:
$ ghci
...
Prelude> :k (->)
(->) :: ?? -> ? -> *
Prelude>
Instead of the expected * -> * -> *
.
What are the ??
and ?
things? Do they mean concrete types or "kind variables"? Or something else?
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