--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/exercises/src/Exercise_3.hs	Wed Nov 07 20:18:58 2012 +0100
@@ -0,0 +1,168 @@
+module Exercise_3 where
+import Data.List
+import Data.Char (isSpace)
+
+{- Library DO NOT CHANGE -}
+type WrapFun = [Char] -> [Char]
+type Picture = [[Char]]
+
+printPicture :: Picture -> IO ()
+printPicture [] = return ()
+printPicture (xs : xss) = do
+  putStrLn xs
+  printPicture xss
+
+pic = [".##.", ".#.#", ".###", "####"]
+{- End Library -}
+
+
+{---------------------------------------------------------------------}
+{- Aufgabe H3.1 -}
+
+snoc :: [a] -> a -> [a]
+snoc [] y = [y]
+snoc (x : xs) y = x : snoc xs y
+
+
+member :: Eq a => a -> [a] -> Bool
+member _ [] = False
+member e (x : xs) = e == x || member e xs
+
+
+butlast :: [a] -> [a]
+butlast [] = []
+butlast [_] = []
+butlast (x : xs) = x : butlast xs
+
+
+{---------------------------------------------------------------------}
+{- Aufgabe G3.2 -}
+
+uniq :: Eq a => [a] -> [a]
+uniq (x:y:ys) = if x == y then uniq (y:ys) else x : uniq (y:ys)
+uniq xs = xs
+
+
+-- Alternativ:
+uniq' :: Eq a => [a] -> [a]
+uniq' [] = []
+uniq' (x:xs) = f x xs
+    where f x [] = [x]
+          f x (y:ys) | x == y = f x ys
+                     | otherwise = x : f y ys
+
+uniqCount :: Eq a => [a] -> [(a, Integer)]
+uniqCount [] = []
+uniqCount (x:xs) = f (x,1) xs
+    where f p [] = [p]
+          f (x,c) (y:ys) | x == y = f (x, c + 1)  ys
+                         | otherwise = (x,c) : f (y, 1) ys
+
+
+
+{---------------------------------------------------------------------}
+{- Aufgabe G3.3 -}
+
+intersep :: a -> [a] -> [a]
+intersep sep (c : c' : cs) = c : sep : intersep sep (c' : cs)
+intersep _ cs = cs
+
+
+andList :: [[Char]] -> [Char]
+andList [] = ""
+andList [w] = w
+andList [w1, w2] = w1 ++ " and " ++ w2
+andList [w1, w2, w3] = w1 ++ ", " ++ w2 ++ ", and " ++ w3
+andList (w : ws) = w ++ ", " ++ andList ws
+
+
+
+{---------------------------------------------------------------------}
+{- Aufgabe G3.4 -}
+
+triangle :: [a] -> [(a, a)]
+triangle [] = []
+triangle (x : xs) = [(x, x') | x' <- xs] ++ triangle xs
+
+
+{- QuickCheck properties -}
+prop_triangle_base = triangle ([] :: [Int]) == []
+prop_triangle_one x = triangle [x] == []
+prop_triangle_two x y = triangle [x, y] == [(x, y)]
+prop_triangle_length xs =
+  length (triangle xs) == n * (n - 1) `div` 2
+  where n = length xs
+prop_triangle_distinct xs =
+  distinct xs ==> distinct (triangle xs)
+  where distinct ys = nub ys == ys
+prop_triangle_complete x xs y ys = (x, y) `elem` triangle (x : xs ++ y : ys)
+prop_triangle_sound1 x y xs =
+  not ((x, y) `elem` triangle (delete x (nub xs)))
+  && not ((y, x) `elem` triangle (delete x (nub xs)))
+prop_triangle_rec x xs =
+  triangle (x : xs) == [(x, x') | x' <- xs] ++ triangle xs
+
+
+
+{---------------------------------------------------------------------}
+{- Aufgabe H3.1 -}
+
+simplifySpaces :: [Char] -> [Char]
+simplifySpaces = undefined
+
+
+
+{---------------------------------------------------------------------}
+{- Aufgabe H3.2 -}
+
+prop_wrap1 :: WrapFun -> [Char] -> Bool
+prop_wrap1 wrap xs = True
+
+prop_wrap2 :: WrapFun -> [Char] -> Bool
+prop_wrap2 wrap xs = True
+
+prop_wrap3 :: WrapFun -> [Char] -> Bool
+prop_wrap3 wrap xs = True
+
+prop_wrap4 :: WrapFun -> [Char] -> Bool
+prop_wrap4 wrap xs = True
+
+prop_wrap5 :: WrapFun -> [Char] -> Bool
+prop_wrap5 wrap xs = True
+
+prop_wrap6 :: WrapFun -> [Char] -> Bool
+prop_wrap6 wrap xs = True
+
+prop_wrap7 :: WrapFun -> [Char] -> Bool
+prop_wrap7 wrap xs = True
+
+prop_wrap8 :: WrapFun -> [Char] -> Bool
+prop_wrap8 wrap xs = True
+
+prop_wrap9 :: WrapFun -> [Char] -> Bool
+prop_wrap9 wrap xs = True
+
+prop_wrap10 :: wrap xsFun -> [Char] -> Bool
+prop_wrap10 wrap xs = True
+
+
+
+{---------------------------------------------------------------------}
+{- Aufgabe H3.3 -}
+
+rotateClockwise :: Picture -> Picture
+rotateClockwise = undefined
+
+
+
+{---------------------------------------------------------------------}
+{- Aufgabe H3.4 -}
+
+{-WETT-}
+sublist :: Eq a => [a] -> [a] -> Bool
+sublist xs ys = undefined
+
+
+subseq :: Eq a => [a] -> [a] -> Bool
+subseq xs ys = undefined
+{-TTEW-}