[Haskell-cafe] Linear shuffle
iakd0 at clusterf.urz.uni-halle.de
Fri Jan 14 04:47:59 EST 2005
On Fri, 14 Jan 2005, Gracjan Polak wrote:
> I want to implement linear list shuffle in Haskell
> (http://c2.com/cgi/wiki?LinearShuffle) and I invented code:
> shuffle :: [a] -> IO [a]
> shuffle  = return 
> shuffle x = do
> r <- randomRIO (0::Int,length x - 1)
> s <- shuffle (take r x ++ drop (r+1) x)
> return ((x!!r) : s)
> This algorithm seems not effective, length, take, drop and (!!) are
> costly. Is there any better way to implement shuffle?
Is it a good idea to use IO monad for this plain computation?
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