25 lines
390 B
Plaintext
25 lines
390 B
Plaintext
module Data.List
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data List a = Null | (:) a (List a)
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(++) :: [a] -> [a] -> [a]
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a ++ [] = a
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[] ++ b = b
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(af:ar) ++ b = af:(ar ++ b)
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null :: [a] -> Bool
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null [] = True
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null _ = False
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length :: [a] -> Word
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length [] = 0
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length (a:rest) = 1 + length rest
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reverse :: [a] -> [a]
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reverse xs = helper xs []
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where
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helper [] acc = acc
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helper (a:rest) acc = helper rest (a:acc)
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