Re: [Haskell-cafe] How to speed things up

28 Apr 2005


      Greg Buchholz wrote:
...
You'd probably get a faster program with Unboxed arrays and
  unsafeAccumArray.
Yeah, its about 20x faster unboxed and unsafe...

import Data.Array.Base

main = print $ quick_func $ take 1000000 $ cycle [1,2,3,1,2,9,1,9]

quick_func :: [Int] -> [(Int,Int)]
quick_func is = assocs f
    where
       f :: UArray Int Int
       f =  unsafeAccumArray (+) 0 (1,12) [(i, 1::Int) | i<-is]