tasks a-s

Task/Queue-Definition/Haskell/queue-definition-3.hs

@@ -0,0 +1,30 @@
+# Use a class to hold a Queue, with a list as the concrete implementation
+class Queue (items)
+  method push (item)
+    put (items, item)
+  end
+
+  # if the queue is empty, this will 'fail' and return nothing
+  method take ()
+    return pop (items)
+  end
+
+  method is_empty ()
+    return *items = 0
+  end
+
+  initially () # initialises the field on creating an instance
+    items := []
+end
+
+procedure main ()
+  queue := Queue ()
+
+  every (item := 1 to 5) do
+    queue.push (item)
+
+  every (1 to 6) do {
+    write ("Popped value: " || queue.take ())
+    if queue.is_empty () then write ("empty queue")
+  }
+end