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{-# OPTIONS_GHC -fno-warn-redundant-constraints #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE UndecidableInstances #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE FunctionalDependencies #-}
{-# LANGUAGE EmptyDataDecls #-}
module T6055 where
data Int1 = Int1
data Word1 = Word1
data D1
data D2
class Succ x y | x -> y
instance Succ D1 D2
class Add' x y z | x y -> z
instance Succ y z => Add' D1 y z
class (Add' x y z) => Add x y z | x y -> z
instance (Add' D1 y z) => Add D1 y z
class IsSized a s | a -> s where
instance IsSized Int1 D1
instance IsSized Word1 D1
instance (IsSized a s, Add s s ns) =>
IsSized (Pair a) ns where
data Pair a = Pair a a
switchFPPred ::
(IsSized v0 s, IsSized v1 s) =>
v0 -> v1
switchFPPred = undefined
cmpss :: Pair Word1 -> Pair Int1
cmpss = switchFPPred
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