Note that the argument, the list to be sorted, is pattern matched as
(p:xs)
greater = filter (>= p) xs
Re:What it's like to use Haskell
by AnimalMuppet on Wednesday March 26, 2014 @03:21PM
(#7475767)
Ah, I see. Thanks!
Re:What it's like to use Haskell
by probably_wrong on Wednesday March 26, 2014 @02:40PM
(#7475425)
If I'm reading the code correctly: given the list [5,5,2,3] and the match (p:xs), p will match to the first 5 and xs will match to [5,2,3].
Once the matching is done, the pivot is no longer in the list xs, and therefore it won't be included twice.
The list is the sorted list of lesser items, then the pivot, then the sorted list of greater items. But since the list of greater items is defined with ">=" rather than just ">", the list of greater items will also contain the pivot. That will put the pivot in the sorted list twice (for each recursive call).