Simple rows script, done as a task for #coders@prooops

rows.hs

{- Simple rows script, done as a task for #coders@prooops 
 - improved by e (thx. for that) -}
import Control.Applicative -- needed for <$> (equal to mapM)
import Control.Monad

main = do
   putStrLn "How many rows do you want to print?"
   y <- read <$> getLine :: IO Int
   let rowsOut = createAstLst y <$> [1..(2*y-1)]
   forM rowsOut putStrLn
 
createAstLst :: Int -> Int -> String
createAstLst x a
  | a < x     = take a $ repeat '*'
  | a == x    = take (2*x-1) $ repeat '*'
  | otherwise = take (2*x-a) $ repeat '*'