--pythagorejske trojice
trojiceNormalne =
  [ (a, b, c) | a <- [1 ..],
                b <- [1 .. a],
                c <- [1 .. b],
                a * a == b * b + c * c ]

--pomucka (interne pouzivana list-comprehensionovou syntaxi)
guard True = [()]
guard False = []

--pythagorejske trojice monadicky (interne to je uplne to same)
trojice = do
  a <- [1 ..]
  b <- [1 .. a]
  c <- [1 .. b]
  guard $ a * a == b * b + c * c
  return (a, b, c)

--pruhlednejsi demonstrace toho jak se aplikativne (a monadicky) chova List
main = print $ [(+ 2), (* 2), negate] <*> [1, 2, 3]