tasks a-s

Task/Queue-Definition/Maxima/queue-definition.maxima

@@ -0,0 +1,18 @@
+defstruct(queue(in=[], out=[]))$
+
+enqueue(x, q) := (q@in: cons(x, q@in), done)$
+
+dequeue(q) := (if not emptyp(q@out) then first([first(q@out), q@out: rest(q@out)])
+elseif emptyp(q@in) then 'fail
+else (q@out: reverse(q@in), q@in: [], first([first(q@out), q@out: rest(q@out)])))$
+
+q:new(queue);    /* queue([], []) */
+enqueue(1, q)$
+enqueue(2, q)$
+enqueue(3, q)$
+dequeue(q);      /* 1 */
+enqueue(4, q)$
+dequeue(q);      /* 2 */
+dequeue(q);      /* 3 */
+dequeue(q);      /* 4 */
+dequeue(q);      /* fail */