1 files changed, 50 insertions, 0 deletions
diff --git a/src/Library/Stack.hs b/src/Library/Stack.hs
new file mode 100644
index 0000000..99cd8e1
--- /dev/null
+++ b/src/Library/Stack.hs
@@ -0,0 +1,50 @@
+module Library.Stack (
+	Stack,
+    empty,
+    at,
+    pop,
+    (<:>),
+    size,
+    diff
+    ) where
+
+
+import Data.List
+
+
+data Stack a = Stack [a] deriving (Eq)
+
+
+instance Show a => Show (Stack a) where
+    show (Stack x)   =   "Stack:\n" ++ intercalate "\n" (map (show) x) ++ "\n\n"
+
+
+infixr 9 <:>
+
+
+empty :: Stack a
+empty = Stack []
+
+
+at :: Stack a -> Int -> Maybe a
+at (Stack list) index =
+    if (index < length list && index >= 0)
+    then Just (list!!index)
+    else Nothing
+
+
+pop :: Int -> Stack a -> Stack a
+pop n (Stack list) = Stack (drop n list)
+
+
+(<:>) :: a -> Stack a -> Stack a
+x <:> (Stack list) = Stack (x : list)
+
+
+size :: Stack a -> Int
+size (Stack list) = length list
+
+
+diff :: (Eq a) => Stack a -> Stack a -> Stack a
+diff (Stack one) (Stack two) = Stack (one \\ two)
+