Taco Shop Namer in Haskell

taco_shop_name.hs

-- run to find out your taco shop name
import System.Random
import Control.Monad.State.Lazy

all_let :: [Char]
all_let = ['a'..'z']

vowels :: [Char]
vowels = "aeiouy"

consonants :: [Char]
consonants = [x | x <- all_let, not $ x `elem` vowels]

getRandChar' :: [Char] -> IO Char
getRandChar' xs = do
  x <- getStdRandom $ randomR (0, (length xs - 1))
  return (xs !! x)

buildVals :: Int -> [Int]
buildVals 0 = 1 : buildVals 1
buildVals 1 = 0 : buildVals 0

makeRandWord :: [Int] -> IO [Char]
makeRandWord ns = sequence [if n == 0 then getRandChar' vowels else getRandChar' consonants | n <- ns]

main = do
  putStrLn "enter total length of taco shop name"
  total_length <- getLine
  let total = (read total_length :: Int) - 6
  g <- getStdGen
  let first = fst $ randomR (0, 1) g
  let randomizer = take total $ buildVals first
  let newWord = makeRandWord randomizer
  newName <- liftM2 (++) newWord ((return "bertos") :: IO [Char])
  -- Alternate (simpler):
  -- fmap (++"bertos") newName
  putStrLn (show newName)