Difference between revisions of "Implicit parameters"
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| − | The GHC manual on implicit parameters: [ |
+ | The GHC manual on implicit parameters: [https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/glasgow_exts.html#implicit-parameters]. |
Working example: |
Working example: |
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import Data.List (sortBy) |
import Data.List (sortBy) |
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| − | + | sortBy' :: (?cmp :: a -> a -> Ordering) => [a] -> [a] |
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| − | + | sortBy' = sortBy ?cmp |
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| + | sort :: Ord a => [a] -> [a] |
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| + | sort = let ?cmp = compare in sortBy' |
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| − | main = |
+ | main = putStrLn (show (sort [3,1,2])) |
[[Category:Language extensions]] |
[[Category:Language extensions]] |
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Revision as of 14:19, 9 July 2016
The GHC manual on implicit parameters: [1].
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]))