choinki haskell

printSpaces :: Int -> IO ()
printSpaces n = putStr (replicate n ' ')

printStars :: Int -> IO ()
printStars n = putStrLn (replicate n '*')

printMirrorUpperStarTriangle :: Int -> Int -> IO ()
printMirrorUpperStarTriangle n x
    | x > n = return ()
    | otherwise = do
        printSpaces (n - x)
        printStars (2 * x - 1)
        printMirrorUpperStarTriangle n (x + 1)

main :: IO ()
main = do
    putStrLn "wprowadz wysokosc: "
    input <- getLine
    let height = read input :: Int
    printMirrorUpperStarTriangle height 1