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{-# OPTIONS_GHC -Woverlapping-patterns #-}
{-# LANGUAGE PatternSynonyms #-}
{-# LANGUAGE ViewPatterns #-}
module Bug (Boolean(F, TooGoodToBeTrue), catchAll) where
data Boolean = F | T
deriving Eq
pattern TooGoodToBeTrue :: Boolean
pattern TooGoodToBeTrue <- ((== T) -> True)
where
TooGoodToBeTrue = T
{-# COMPLETE F, TooGoodToBeTrue #-}
catchAll :: Boolean -> Int
catchAll F = 0
catchAll TooGoodToBeTrue = 1
catchAll F = 2
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