Added definitions / examples

documents/Programmierparadigmen/scripts/haskell/standard-definitions.hs

@@ -0,0 +1,38 @@
+map :: (a -> b) -> [a] -> [b]
+map f []     = []
+map f (x:xs) = f x : map f xs
+----------
+
+zipWith          :: (a->b->c) -> [a]->[b]->[c]
+zipWith z (a:as) (b:bs)
+                 =  z a b : zipWith z as bs
+zipWith _ _ _    =  []
+----------
+
+zip              :: [a] -> [b] -> [(a,b)]
+zip              =  zipWith (,)
+----------
+
+unzip            :: [(a,b)] -> ([a],[b])
+unzip            =  foldr (\(a,b) ~(as,bs) -> (a:as,b:bs)) ([],[])
+----------
+
+foldl            :: (a -> b -> a) -> a -> [b] -> a
+foldl f z []     =  z
+foldl f z (x:xs) =  foldl f (f z x) xs
+----------
+
+foldr            :: (a -> b -> b) -> b -> [a] -> b
+foldr f z []     =  z
+foldr f z (x:xs) =  f x (foldr f z xs)
+----------
+
+take                   :: Int -> [a] -> [a]
+take n _      | n <= 0 =  []
+take _ []              =  []
+take n (x:xs)          =  x : take (n-1) xs
+----------
+
+splitAt                  :: Int -> [a] -> ([a],[a])
+splitAt n xs             =  (take n xs, drop n xs)
+----------