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a-hisame/non-implements-eq.hs

Created September 3, 2014 08:31
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当たり前だけれど、Eqのデフォルト実装を上書きしない場合、無限ループに陥る。
Raw
non-implements-eq.hs
-- test on ghci console
data Present a = Redbox a | Bluebox a deriving Show
instance Eq (Present a)
let a = Redbox 10
let b = Redbox 30
-- never stop
a == b
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