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Kind

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* [[GHC/Kinds]]
 
* [[GHC/Kinds]]
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* [http://hackage.haskell.org/trac/ghc/wiki/IntermediateTypes#KindsareTypes Kinds ?, ??, # and (#)]
   
 
[[Category:Language]]
 
[[Category:Language]]

Revision as of 05:58, 15 November 2011

Kinds classify types. Kinds are to types and type-constructors what types are to values.

Ordinary types have kind *. Type constructors have kind P -> Q, where P and Q are kinds. For instance:

Int :: *
Maybe :: * -> *
Maybe Bool :: *
a -> a :: *
[] :: * -> *
(->) :: * -> * -> *

In Haskell 98, * is the only inhabited kind, that is, all values have types of kind *. GHC introduces another inhabited kind, #, for unboxed types.

See also