23 lines
624 B
TeX
23 lines
624 B
TeX
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Imagine we want to filter all even numbers of a list and throw away all others. I'll give you the type signature:
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\begin{haskellcode}
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filterEven :: [Int] -> [Int]
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\end{haskellcode}
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Solution?
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\pause
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\begin{haskellcode}
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filterEven :: [Int] -> [Int]
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filterEven [] = []
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filterEven (x:xs)
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| even x = x : filterEven xs
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| otherwise = filterEven xs
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\end{haskellcode}
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\pause
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Or: filter out all 0's, so we can count them later:
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\begin{haskellcode}
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filterZero :: [Int] -> [Int]
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filterZero [] = []
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filterZero (x:xs)
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| x == 0 = x : filterZero xs
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| otherwise = filterZero xs
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\end{haskellcode}
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Again: do you notice something?
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