Difference between revisions of "Talk:Higher order function"
Yasmin.Fathy (talk | contribs) |
(Added an answer) |
||
Line 6: | Line 6: | ||
---- |
---- |
||
− | quicksort :: Ord a => [a] -> [a] |
+ | quicksort :: Ord a => [a] -> [a] |
− | quicksort [] = [] |
+ | quicksort [] = [] |
− | quicksort (p:xs) = (quicksort lesser) ++ [p] ++ (quicksort greater) |
+ | quicksort (p:xs) = (quicksort lesser) ++ [p] ++ (quicksort greater) |
− | where |
+ | where |
− | lesser = filter (< p) xs |
+ | lesser = filter (< p) xs |
− | greater = filter (>= p) xs |
+ | greater = filter (>= p) xs |
---- |
---- |
||
Line 20: | Line 20: | ||
Thanks in advance |
Thanks in advance |
||
+ | |||
+ | ---- |
||
+ | |||
+ | You can better ask this sort of questions via the [http://haskell.org/mailman/listinfo/beginners Haskell-beginners mailinglist] or [http://stackoverflow.com/ 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. |
||
+ | |||
+ | <hask>xs ++ ys</hask> concatenates the lists <hask>xs</hask> and <hask>ys</hask> |
||
+ | |||
+ | 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. |
||
+ | |||
+ | |||
+ | [[User:Henk-Jan van Tuyl|Henk-Jan van Tuyl]] 10:24, 10 November 2011 (UTC) |
Latest revision as of 10:24, 10 November 2011
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)