testsuite/tests/arrows/should_compile/T3964.hs


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{-# LANGUAGE Arrows, ViewPatterns #-}

module T3964 where

import Control.Arrow

testF :: Eq a => a -> (Maybe (Maybe a)) -> Maybe a
testF v = proc x -> case x of
     Just (Just ((==v) -> True)) -> returnA -< Just v
     _                           -> returnA -< Nothing