This package contains functions for performing in-place Fisher--Yates shuffles on mutable and immutable vectors along with some related functionality. The shuffles are uniform at random amongst all permuations.

For an example of how to use it:

module Main where

import Data.Vector
import Immutable.Shuffle

main :: IO ()
main = do {
shuffleMyVector >>= print;
cycleMyVector   >>= print;
derangeMyVector >>= print;
}

myVector :: Vector Int
myVector = fromList [1..10]

shuffleMyVector :: IO (Vector Int)
shuffleMyVector = shuffleM myVector

cycleMyVector :: IO (Vector Int)
cycleMyVector = maximalCycleM myVector

derangeMyVector :: IO (Vector Int)
derangeMyVector = derangementM myVector

This gives the following:

>>> main
[2,8,1,5,10,9,7,3,6,4]
[6,8,4,10,9,2,5,7,3,1]
[8,5,4,1,10,9,3,6,2,7]

>>> main
[7,9,3,5,10,6,8,1,2,4]
[2,4,10,7,8,1,5,9,3,6]
[4,8,5,2,7,3,9,6,10,1]