Difference between revisions of "Implicit parameters"

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{{GHCUsersGuide|glasgow_exts|implicit-parameters|Implicit Parameters section}}
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{{GHCUsersGuide|glasgow_exts|implicit-parameters|an Implicit Parameters section}}
   
 
Working example:
 
Working example:

Latest revision as of 00:28, 14 November 2016

The GHC Users Guide has an Implicit Parameters section.

Working example:

{-# LANGUAGE ImplicitParams #-}

import Data.List (sortBy)

sortBy' :: (?cmp :: a -> a -> Ordering) => [a] -> [a]
sortBy' = sortBy ?cmp
sort :: Ord a => [a] -> [a]
sort = let ?cmp = compare in sortBy'

main = putStrLn (show (sort [3,1,2]))