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|
{-# LANGUAGE Arrows, LambdaCase #-}
module Main (main) where
import Control.Arrow
main :: IO ()
main = do
putStrLn $ foo (Just 42)
putStrLn $ foo (Just 500)
putStrLn $ foo Nothing
foo :: ArrowChoice p => p (Maybe Int) String
foo = proc x ->
(| id (\case
Just x | x > 100 -> returnA -< "big " ++ show x
| otherwise -> returnA -< "small " ++ show x
Nothing -> returnA -< "none")
|) x
foo :: ArrowChoice p => p (Maybe Int) String
foo = proc x ->
(| id (\cases
y (Just x) | x > 100 -> returnA -< "big " ++ show x
| otherwise -> returnA -< "small " ++ show x
_ Nothing -> returnA -< "none")
|) 1 x
|
