Various comments on problematic aspects of the code.

collects/unstable/queue.rkt

@@ -1,13 +1,20 @@
 #lang racket
+;; ELI: why is it using the `racket' language?
 
 ;; A Queue is a circularly linked list of queue structures.
 ;; The head of the circle is identified by the distinguished head value.
 ;; The top of the queue (front of the line) is to the right of the head.
 ;; The bottom of the queue (back of the line) is to the left of the head.
+;; ELI: need to say that this is not thread-safe.
 (define-struct queue (value left right) #:mutable)
+;; ELI: why is `value' mutable?
 
+;; ELI: why is this needed, if nobody can get a hold of anything other
+;; than the head?
 (define head (gensym 'queue-head))
 
+;; ELI: if it's a single direction queue, then why is it maintaining
+;; bidirectional links?
 (define (empty-queue)
   (let* ([q (make-queue head #f #f)])
     (set-queue-left! q q)
@@ -17,16 +24,16 @@
 (define (queue-head? q)
   (eq? (queue-value q) head))
 
-(define (head-queue? v)
+(define (head-queue? v) ; ELI: `queue-head?' and `head-queue?' --??
   (and (queue? v) (queue-head? v)))
 
 (define (queue-empty? q)
   (and (queue-head? q) (queue-head? (queue-right q))))
 
 (define (nonempty-queue? v)
-  (and (queue? v)
-       (queue-head? v)
-       (queue? (queue-right v))
+  (and (queue? v)      ; \ ELI: ...and this is `head-queue?'
+       (queue-head? v) ; /
+       (queue? (queue-right v)) ; ELI: can this ever be false?
        (not (queue-head? (queue-right v)))))
 
 (define (enqueue! q v)