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{-# LANGUAGE GADTs #-}
{-# LANGUAGE PatternSynonyms #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE TypeInType #-}
{-# LANGUAGE TypeOperators #-}
{-# OPTIONS_GHC -Wincomplete-patterns #-}
module Bug where
data family Sing (a :: k)
data instance Sing (z :: Bool) where
SFalse :: Sing False
STrue :: Sing True
pattern STooGoodToBeTrue :: forall (z :: Bool). ()
=> z ~ True
=> Sing z
pattern STooGoodToBeTrue = STrue
{-# COMPLETE SFalse, STooGoodToBeTrue #-}
wibble :: Sing (z :: Bool) -> Bool
wibble STrue = True
wobble :: Sing (z :: Bool) -> Bool
wobble STooGoodToBeTrue = True
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