module W04_3
where

import Prelude hiding (dropWhile, takeWhile)

-- Drop a consecutive block of elements fulfilling the given predicate
--
-- Example: dropWhile (< 5) [1, 2, 3, 4, 5, 6] = [5, 6]
--
dropWhile                      :: (a -> Bool) -> [a] -> [a]
dropWhile p []                  = []				-- DELETE
dropWhile p (x:xs) | p x        = dropWhile p xs		-- FOR THE
		   | otherwise  = x:xs				-- LECTURE

-- Retain a consecutive block of elements fulfilling the given predicate
--
-- Example: dropWhile (< 5) [1, 2, 3, 4, 5, 6] = [1, 2, 3, 4]
--
takeWhile :: (a -> Bool) -> [a] -> [a]
takeWhile p []                  = []				-- DELETE
takeWhile p (x:xs) | p x        = x : takeWhile p xs		-- FOR THE
		   | otherwise  = []				-- LECTURE