Haskell - Prázdny trojuholník (zdrojový kód .hs)

Haskell - Prázdny trojuholník - zdrojovy kod .hs
-- prazdny trojuholnik --

a :: Int
a = 10

zoznam = [ x | x <- [-1..a-2] ]

riadok (x:xs) | x == -1 = "*" : riadok xs
| x == a - 2 = [copy a '*']
| otherwise = ("*" ++ copy x ' ' ++ "*") : riadok xs

copy n x = take n (repeat x)

prazdnyTrojuholnik = unlines (riadok zoznam)

p1 = putStr prazdnyTrojuholnik

-- pondelkova skupina - uloha --

rjustify n s = space (n - length s) ++ s
space n = [ ' ' | i <- [1..n]]

p2 = putStr (unlines (map (rjustify 20) (lines prazdnyTrojuholnik) ))
...