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Talk:Higher order function

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I'm a beginner in Haskell and needs help I need a resourse of haskell from scratch and also need someone to explain in details the quicksort that is published:



quicksort :: Ord a => [a] -> [a]
quicksort []     = []
quicksort (p:xs) = (quicksort lesser) ++ [p] ++ (quicksort greater)
    where
        lesser  = filter (< p) xs
        greater = filter (>= p) xs


without line no 1, it works fine what about line three ? and how we use ++ as concatenate ???

Thanks in advance


You can better ask this sort of questions via the Haskell-beginners mailinglist or StackOverflow; the talk pages are usually used for discussion of a wikipage.

There are tutorials listed at http://www.haskell.org/haskellwiki/Tutorials

Line no. 1 is correct, it describes the type of the function.

xs ++ ys
concatenates the lists
xs
and
ys

You can find a description of how this function works at http://learnyouahaskell.com/recursion ; the function at this pages looks different, but is actually the same.


Henk-Jan van Tuyl 10:24, 10 November 2011 (UTC)