48 lines
737 B
Plaintext
48 lines
737 B
Plaintext
module Data.List
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export datatype List a =
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NULL()
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| (:)(a,List a);
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export (++)(a :: [a], b :: [a]) :: [a]
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{
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case a of
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[] -> b
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(af:ar) -> case b of
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[] -> a
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_ -> af:(ar ++ b)
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};
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export null(ls :: [a]) :: Bool
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{
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case ls of
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[] -> True
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_ -> False
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};
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export length(ls :: [a]) :: Int
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{
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case ls of
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[] -> 0
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_:rest -> length rest
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};
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export reverse(ls :: [a]) :: [a]
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{
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helper(xs,acc) = {
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case xs of
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[] -> acc
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(a:rest) -> helper rest (a:acc)
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}
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helper ls [];
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};
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export restrict(Eq a) find(f :: a -> Bool, ls :: [a]) :: Maybe a
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{
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case ls of
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[] -> False
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(a:_) | f a -> a
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(_:rest) -> find(f, rest)
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};
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