Talk:Higher order function
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
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
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)