#!/usr/bin/runghc
-- These methods are PRNG for statistics, not cryptography

module RandomExample where

import System.Random

main :: IO ()
main = do
  -- Single item, ranged
  singleIntRange <- randomRIO (1, 10) :: IO Int
  print singleIntRange

  singleFloatRange <- randomRIO (1, 10) :: IO Float
  print singleFloatRange

  singleCharRange <- randomRIO ('a', 'z') :: IO Char
  print singleCharRange

  -- Single item, default range bounds
  singleIntDefault <- randomIO :: IO Int
  print singleIntDefault

  singleCharDefault <- randomIO :: IO Char
  print singleCharDefault

  -- Single item, ranged
  rollDice <- getStdRandom (randomR ('a', 'z'))
  print rollDice

  rollDice2 <- getStdRandom (randomR (1, 10 :: Int))
  print rollDice2

  -- Single item, default range
  rollDiceInt <- getStdRandom random :: IO Int
  print rollDiceInt

  rollDice2Char <- getStdRandom random :: IO Char
  print rollDice2Char

  -- You can choose the seed:
  s1 <- getStdGen
  let (i1, s2) = randomR (0, 100 :: Int) s1

  -- The seed is passed, then chained:
  let (i2, s3) = randomR (0, 100) s2 :: (Float, StdGen)

  -- Default range
  let (i3, s4) = random s3 :: (Int, StdGen)
  putStrLn $ show i1 ++ ", " ++ show i2 ++ ", " ++ show i3

  -- Using a seed, generate list of ranged ints, ranged
  let randList = take 20 $ randomRs (0, 99 :: Int) s4
  print randList

  -- Generate list of ranged Chars, default range
  putStrLn $ take 20 (randomRs ('a', 'z') s4)

  -- You can choose the seed alternatively:
  let rs = mkStdGen 42
  let randFloats = take 20 $ randoms rs :: [Float]
  print randFloats