add stack and queue

Author: cd155

src/StackQueue.hs

@@ -0,0 +1,25 @@
+module StackQueue where
+
+newtype Stack a = Stack [a] deriving Show
+
+emptyS = Stack []
+
+pop :: Stack a -> Maybe (Stack a, a)
+pop (Stack []) = Nothing
+pop (Stack (x:xs)) = Just (Stack xs, x)
+
+push :: a -> Stack a -> Stack a
+push x (Stack l) = Stack (x:l)
+
+newtype Queue a = Queue [a] deriving Show
+
+emptyQ = Queue []
+
+deQue :: Queue a -> Maybe (Queue a, a)
+deQue (Queue []) = Nothing
+deQue (Queue xs) = Just (Queue (init xs), last xs)
+
+enQue :: a -> Queue a -> Queue a
+enQue x (Queue l) = Queue (l++[x])
+
+-- alternative the list can be use as Stack or Queue