42 lines
935 B
Haskell
42 lines
935 B
Haskell
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myMap :: (a -> b) -> [a] -> [b]
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-- myMap f [] = []
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-- myMap f (x : xs) = (f x) : (myMap f xs)
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-- inputs: [a, b, c]
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-- desired output: [a', b', c']
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-- non end recursive result:
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-- myMap f [a, b, c]
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-- (f a) : (myMap f [b, c])
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-- (f a) : ((f b) : (myMap f [c]))
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-- (f a) : ((f b) : ((f c) : myMap f []))
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-- (f a) : ((f b) : ((f c) : myMap f []))
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-- (f a) : ((f b) : ((f c) : []))
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-- a' : (b' : (c' : []))
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-- [a', b', c']
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-- ((a' : b') : c')
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-- ((f a) : (f b)) : f c
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myMap f = realMap []
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where
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realMap acc [] = acc
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realMap acc (x : xs) = realMap (acc ++ [f x]) xs
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-- >>> myMap ((+1)) [0, 2, 2, 6]
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-- [1,3,3,7]
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--
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fakTR :: Integer -> Integer
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fakTR = fakTR_ 1
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where
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fakTR_ :: Integer -> Integer -> Integer
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fakTR_ acc 0 = acc
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fakTR_ acc n = fakTR_ (n * acc) (n -1)
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fakC :: Integer -> Integer
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fakC = fakC_ (const 1)
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where
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fakC_ f n
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| n == 0 = f n
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| otherwise = fakC_ (\ x -> n * (f x)) $ n - 1
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