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Implicit parameters

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The GHC manual on implicit parameters: [http://www.haskell.org/ghc/docs/latest/html/users_guide/other-type-extensions.html#implicit-parameters].
 
The GHC manual on implicit parameters: [http://www.haskell.org/ghc/docs/latest/html/users_guide/other-type-extensions.html#implicit-parameters].
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Working example:
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{-# LANGUAGE ImplicitParams #-}
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import Data.List (sortBy)
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sort :: (?cmp :: a -> a -> Ordering) => [a] -> [a]
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sort = sortBy ?cmp
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main = let ?cmp = compare in putStrLn (show (sort [3,1,2]))
   
 
[[Category:Language extensions]]
 
[[Category:Language extensions]]

Latest revision as of 18:41, 18 December 2012

The GHC manual on implicit parameters: [1].

Working example:

{-# LANGUAGE ImplicitParams #-}

import Data.List (sortBy)

sort   :: (?cmp :: a -> a -> Ordering) => [a] -> [a]
sort    = sortBy ?cmp

main = let ?cmp = compare in putStrLn (show (sort [3,1,2]))