23 lines
392 B
Haskell
23 lines
392 B
Haskell
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newtype Boxed a = Boxed {unbox :: a}
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instance Functor Boxed where
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fmap f (Boxed a) = Boxed (f a)
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test1 = unbox (fmap id b) == unbox b
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where
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b = Boxed { unbox = 1 :: Integer }
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-- >>> test1
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-- True
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--
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test2 = unbox (fmap (f . g) b) == unbox (fmap f $ fmap g b)
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where
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b = Boxed { unbox = 1 :: Integer }
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f = (+9)
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g = (*11)
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-- >>> test2
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-- True
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--
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