diff --git a/functional-queue.rkt b/functional-queue.rkt
new file mode 100644
index 0000000..e7f5772
--- /dev/null
+++ b/functional-queue.rkt
@@ -0,0 +1,80 @@
+#lang racket/base
+
+(provide make-queue
+	 queue?
+	 enqueue
+	 enqueue-all
+	 dequeue
+	 list->queue
+	 queue->list
+	 queue-length
+	 queue-empty?
+	 queue-append
+	 queue-append-list
+	 queue-extract)
+
+(struct queue (head tail) #:transparent)
+
+(define (make-queue)
+  (queue '() '()))
+
+(define (enqueue q v)
+  (queue (queue-head q)
+	 (cons v (queue-tail q))))
+
+(define (enqueue-all q v)
+  (queue (queue-head q)
+	 (append (reverse v) (queue-tail q))))
+
+(define (shuffle q)
+  (if (null? (queue-head q))
+      (queue (reverse (queue-tail q)) '())
+      q))
+
+(define (dequeue q)
+  (let ((q1 (shuffle q)))
+    (values (car (queue-head q1))
+	    (queue (cdr (queue-head q1)) (queue-tail q1)))))
+
+(define (list->queue xs)
+  (queue xs '()))
+
+(define (queue->list q)
+  (append (queue-head q) (reverse (queue-tail q))))
+
+(define (queue-length q)
+  (+ (length (queue-head q))
+     (length (queue-tail q))))
+
+(define (queue-empty? q)
+  (and (null? (queue-head q))
+       (null? (queue-tail q))))
+
+(define (queue-append q1 q2)
+  (queue (append (queue-head q1)
+		 (reverse (queue-tail q1))
+		 (queue-head q2))
+	 (queue-tail q2)))
+
+(define (queue-append-list q1 xs)
+  (queue (queue-head q1)
+	 (append (reverse xs) (queue-tail q1))))
+
+(define (queue-extract q predicate [default-value #f])
+  (let search-head ((head (queue-head q))
+		    (rejected-head-rev '()))
+    (cond
+     ((null? head) (let search-tail ((tail (reverse (queue-tail q)))
+				     (rejected-tail-rev '()))
+		     (cond
+		      ((null? tail) (values default-value q))
+		      ((predicate (car tail)) (values (car tail)
+						      (queue (queue-head q)
+							     (append (reverse (cdr tail))
+								     rejected-tail-rev))))
+		      (else (search-tail (cdr tail) (cons (car tail) rejected-tail-rev))))))
+     ((predicate (car head)) (values (car head)
+				     (queue (append (reverse rejected-head-rev)
+						    (cdr head))
+					    (queue-tail q))))
+     (else (search-head (cdr head) (cons (car head) rejected-head-rev))))))