[vector] #45: fromList/sort performance problems

[vector]

#45: fromList/sort performance problems
-------------------+--------------------------------------------------------
Reporter:  rl      |       Owner:     
    Type:  defect  |      Status:  new
Priority:  major   |   Milestone:  0.8
 Version:  0.7     |    Keywords:     
-------------------+--------------------------------------------------------
 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.

-- 
Ticket URL: <http://trac.haskell.org/vector/ticket/45>
vector <http://trac.haskell.org/vector>
Package vector