fact x
     | (x<0)       =0
	 | x==0        =1
	 |otherwise = x *fact (x-1)

fact' x
	| x < 0 = 0
fact' 0 = 1
fact' x = x * fact (x-1)

fact'' 0 = 1
fact'' x = x * fact'' (x-1)

h x
	| x < 0 = 0
	| otherwise = fact'' x
	where
		fact'' :: Integral a => a -> a
		fact'' 0 = 1
		fact'' x = x * fact'' (x-1)

listApp :: [a -> b] -> a -> [b]
listApp [] _    = []
listApp (x:xs) a =  x a : listApp xs a

isPrefixOf []        _ = True
isPrefixOf _         []= False
isPrefixOf (x:xs) (y:ys) =x == y && isPrefixOf xs ys

nub []     = []
nub (x:xs) = x : nub [a | a <- xs, a /=x]

polinom []    _ = 0
polinom (x:xs) a = x + a * polinom xs a

runs _ [] = []
runs n l = take n l : runs n (drop n l)

slice (x:xs) l = take x l : slice xs (drop x l)
slice _ _ = []

every _ [] = []
every n (x:xs) = x : every n (drop (n-1) xs)

tails []     = [[]]
tails (x:xs) = (x:xs) : tails xs

tails []     = [[]]
tails list@(_:xs) = list : tails xs