2015-04-19 22:32:01 +00:00
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Again, we can do pattern matching on lists.
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\begin{haskellcode}
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listLen :: [Integer] -> Integer
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listLen [] = 0
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listLen (x:xs) = 1 + listLen xs
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\end{haskellcode}
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\pause
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We can also nest pattern matching:
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\begin{haskellcode}
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sumEveryTwo :: [Integer] -> [Integer]
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sumEveryTwo [] = 0
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sumEveryTwo (x:[]) = [x]
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sumEveryTwo (x:(y:zs)) = (x + y) : sumEveryTwo zs
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\end{haskellcode}
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2015-04-20 18:55:41 +00:00
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Note that \hinline{(x:(y:zs))} may also be written as \hinline{(x:y:zs)}.
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