lab08: init

lab08/stack.hs

@@ -0,0 +1,29 @@
+import Control.Monad.State
+
+type Stack = [Int]
+
+pop :: Stack -> (Int,Stack)
+pop (x:xs) = (x,xs)
+
+push :: Int -> Stack -> ((),Stack)
+push a xs = ((),a:xs)
+
+stackManip :: Stack -> (Int, Stack)  
+stackManip stack = let  
+    ((),newStack1) = push 3 stack  
+    (a ,newStack2) = pop newStack1  
+    in pop newStack2 
+
+
+pop' :: State Stack Int
+pop' = State $ \(x:xs) -> (x,xs)
+
+push' :: Int -> State Stack ()
+push' a = State $ \xs -> ((),a:xs)
+
+stackManip' :: State Stack Int
+stackManip' = do
+  push' 3
+  a <- pop'
+  pop'
+