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Example
map even $ maybeToList $ Just 5
yields the same as
maybeToList $ map even $ Just 5
yields: both yield
Vertical arrows
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maybeToList :: Maybe Int -> [Int]
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Nothing
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[]
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Just 0
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[0]
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Just 1
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[1]
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maybeToList :: Maybe Bool -> [Bool]
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Nothing
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[]
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Just True
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[True]
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Just False
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[False]
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Horizontal arrows
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map even:: Maybe Int -> Maybe Bool
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Nothing
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Nothing
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Just 0
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Just True
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Just 1
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Just False
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map even:: [Int] -> [Bool]
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[]
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[]
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[0]
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[T]rue
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[1]
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[F]alse
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Commutativity of diagram
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map even . maybeToList
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maybeToList . map even
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Nothing
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[]
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[]
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Just 0
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[True]
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[True]
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Just 1
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[False]
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[False]
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