id	summary	reporter	owner	description	type	status	priority	milestone	version	resolution	keywords	cc
45	fromList/sort performance problems	rl		"Reportedly, this is slow:

{{{
import Prelude hiding (sum)

import Data.Vector.Algorithms.Combinators (apply)
import Data.Vector.Algorithms.Intro (sort)
import Data.Vector.Unboxed (Vector, Unbox, fromList, sum)

vsort :: (Unbox a, Ord a) => [a] -> Vector a
vsort = apply sort . fromList

list :: [Int]
list = takeWhile (> 0) $ iterate (subtract 1) 10000000

main = do
	print $ sum $ vsort list
}}}

And this is fast:

{{{
import Prelude hiding (sum)

import Control.Monad (zipWithM_)
import Data.Vector.Algorithms.Intro (sort)
import Data.Vector.Generic (create)
import Data.Vector.Unboxed (Vector, Unbox, sum)
import Data.Vector.Unboxed.Mutable (new, write)

vsort :: (Unbox a, Ord a) => [a] -> Vector a
vsort list = create $ do
	v <- new (length list)
	zipWithM_ (\i x -> write v i x) [0..] list
	sort v
	return v

list :: [Int]
list = takeWhile (> 0) $ iterate (subtract 1) 10000000

main = do
	print $ sum $ vsort list
}}}

Also, boxed vector seem to kill performance here."	defect	closed	critical	0.7.1	0.7	invalid