Initial data commit

Task/Stack/Common-Lisp/stack.lisp

@@ -0,0 +1,16 @@
+(defstruct stack
+  elements)
+
+(defun stack-push (element stack)
+  (push element (stack-elements stack)))
+
+(defun stack-pop (stack)(deftype Stack [elements])
+
+(defun stack-empty (stack)
+  (endp (stack-elements stack)))
+
+(defun stack-top (stack)
+  (first (stack-elements stack)))
+
+(defun stack-peek (stack)
+  (stack-top stack))