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{-# LANGUAGE Arrows, GeneralizedNewtypeDeriving #-}
module T5267 where
import Prelude
import Control.Arrow
import Control.Category
newtype A a b c = A { unA :: a b c }
deriving (Category, Arrow)
ite :: ArrowChoice a
=> a env Bool -> A a env d -> A a env d -> A a env d
ite iA tA eA = A $ proc env ->
do i <- iA -< env
if i then unA tA -< env else unA eA -< env
ite_perm tA eA i = ite i tA eA
-- In 6.12, this worked:
ite' cA tA eA = proc x ->
do c <- cA -< x
(| (ite_perm tA eA) (returnA -< c) |)
-- but this didn't:
ite'' cA tA eA = proc x ->
do c <- cA -< x
(| ite_perm' (returnA -< c) |)
where ite_perm' i = ite i tA eA
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