import System.Random
import Control.Monad(when)
import Control.Monad.State.Lazy

consonants :: [Char]
consonants = "bcdfghjklmnpqrstvwxyz"

vowels :: [Char]
vowels = "aeiou"

randomInt :: (Int, Int) -> State StdGen Int
randomInt bounds = do
    gen <- get
    let (result, newGen) = randomR bounds gen
    put newGen
    return result

random2 :: Int -> State StdGen Int
random2 n = randomInt (0, n - 1)

randomChoose :: [a] -> State StdGen a
randomChoose l = do
    index <- random2 $ length l
    return $ l !! index

randomConsonant :: State StdGen Char
randomConsonant = randomChoose consonants

randomVowel :: State StdGen Char
randomVowel = randomChoose vowels

randomReplicate :: (Int, Int) -> a -> State StdGen [a]
randomReplicate bounds x = do
    n <- randomInt bounds
    return $ replicate n x

main = do
    seed <- randomIO
    let str = fst $ runState genSyllable $ mkStdGen seed
    putStrLn $ "Syllable is " ++ str

genSyllable :: State StdGen String
genSyllable = do
   beg <- randomReplicate (0, 3) randomConsonant
   mid <- randomReplicate (1, 2) randomVowel
   end <- randomReplicate (0, 3) randomConsonant
   let all = concat [beg, mid, end]
   sequence all