Code for 29 feb.

2016-02-29/DataTypes.hs

@@ -0,0 +1,47 @@
+module DataTypes where
+
+data User = NormalUser { userName :: String
+                       , userAge  :: Int }
+          | Admin { userName  :: String
+                  , userAge   :: Int
+                  , adminRole :: String }
+          deriving (Show)
+
+data FileAccessMode = Read | Write | Append
+
+data Expr = IntLiteral Int
+          | StringLiteral String
+          | Addition Expr Expr
+
+showUser :: User -> String
+showUser (NormalUser name age) =
+  ("Name: " ++ name ++ " Age: " ++ show age)
+showUser (Admin name age role) =
+  ("Name: " ++ name ++ " Age: " ++ show age ++ " Role: " ++ role)
+
+data IntList = EmptyList | List Int IntList
+
+iNull :: IntList -> Bool
+iNull x = case x of { EmptyList -> True; _ -> False }
+
+iLen :: IntList -> Int
+iLen x = case x of { EmptyList -> 0; List i rest -> 1 + iLen rest }
+
+iSum x = case x of { EmptyList -> 0; List i rest -> i + iSum rest }
+iDouble x = case x of { EmptyList -> EmptyList;
+                        List i rest -> iDouble (List (i*2) rest) }
+iEven x = case x of { EmptyList -> EmptyList;
+                      List a rest -> if even a then List a (iEven rest) else iEven rest }
+
+data BST = EmptyNode | Node {left::BST, value::Int, right::BST} deriving (Show)
+
+inOrder :: BST -> [Int]
+inOrder EmptyNode    = []
+inOrder (Node l v r) = inOrder l ++ [v] ++ inOrder r
+
+find :: BST -> Int -> Bool
+find EmptyNode _ = False
+find n@(Node l v r) x
+  | x == v    = True
+  | x > v     = find r x
+  | otherwise = find l x