isSquare xs = all (True &&) (map (\(ys,_) -> length xs == length ys) xs)

multAndAdd a xs ys = add (mul a xs) ys
	where
		mul a (xs,y) = (map (a*) xs, a*y)
		add (xs,y) (ys,z) = (zipWith (+) xs ys, y+z)

reorder fkt xs = rH xs []
	where
		rH [] ys = ys
		rH (x:xs) ys
			| fkt x = x:(ys++xs)
			| otherwise = rH xs (ys++[x])