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28 lines
788 B
28 lines
788 B
7 years ago
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module Person where
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validateLength :: Int -> String -> Maybe String
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validateLength maxLen s =
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if (length s) > maxLen
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then Nothing
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else Just s
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newtype Name = Name String deriving (Eq, Show)
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newtype Address = Address String deriving (Eq, Show)
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mkName :: String -> Maybe Name
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mkName s = fmap Name $ validateLength 25 s
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mkAddress :: String -> Maybe Address
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mkAddress a = fmap Address $ validateLength 100 a
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data Person = Person Name Address deriving (Eq, Show)
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mkPerson :: String -> String -> Maybe Person
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-- mkPerson n a =
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-- case mkName n of
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-- Nothing -> Nothing
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-- Just n' ->
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-- case mkAddress a of
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-- Nothing -> Nothing
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-- Just a' -> Just $ Person n' a'
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mkPerson n a = Person <$> mkName n <*> mkAddress a
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