Example on how to generate a lazy stream of random numbers in haskell using System.IO.Unsafe

LazyRandom.hs

import System.IO.Unsafe ( unsafeInterleaveIO )
import System.Random ( randomRIO )
import Text.Printf ( printf )

-- | An infinite list of random die rolls, lazily generated
--
-- This is dangerous since calling this function steps the global random generator
-- not when running the action, but when accessing its result.
diceRolls :: IO [Int]
diceRolls = do
    x <- randomRIO (1,6)
    xs <- unsafeInterleaveIO diceRolls
    return (x:xs)

main :: IO ()
main = do
    -- The type of `rolls` is [Int], but accessing elements in that list will have side effects! 🤯
    rolls <- diceRolls 
    printf "It took %d rolls to get a 6 on the die." . (+ 1) . length . takeWhile (/= 6) $ rolls