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copied!<p>The error you're referring to could be caused, I believe, by having the language level set incorrectly in your "queue.rkt" file. In particular, the language for all three of these should be set to</p> <p>"Use Language Declared in Source".</p> <p>Honestly, I'm really not sure why you're building this as three separate modules; I think it's causing you additional difficulty, but it should certainly be possible to do it this way.</p> <p>Edit: looks like you have paren problems. In particular, you have three close-parens after your definition of 'size'. Does DrRacket not highlight this problem for you when you run?</p> <p>Edit 2: ooh, yucky: you're using "include". Don't use include. </p> <p>Edit 3: Okay, here: I reformatted your code to be in one file:</p> <pre><code>(module queue racket (require rackunit) (provide make-queue enqueue dequeue top size) (struct queue (front back size) #:mutable #:transparent) (define (make-queue) (queue null null 0)) (define (enqueue q elt) (set-queue-back! q (cons elt (queue-back q))) (set-queue-size! q (+ (queue-size q) 1)) ) (define (dequeue q) (cond ((eq? (queue-size q) 0) null) ((null? (queue-front q)) (begin (set-queue-front! q (cdr (reverse (queue-back q)))) (set-queue-back! q null) (set-queue-size! q (- (queue-size q) 1)))) (else (begin (set-queue-front! q (cdr (queue-front q))) (set-queue-size! q (- (queue-size q) 1)))) ) ) (define (top q) (cond ((eq? (queue-size q) 0) null) ((null? (queue-front q)) (last (queue-back q))) (else (car (queue-front q))))) (define (size q) (queue-size q)) (test-case "Initial Queue Properties" (let ((q (make-queue))) (check-equal? (size q) 0 "Queue initially should have size zero.") (check-equal? (dequeue q) null "Dequeue on an empty queue returns null") (check-equal? (size q) 0 "Dequeue on empty queue leaves size as zero") )) (test-case "One Element queue ---- Functional test" (let ((q (make-queue))) (check-equal? (size q) 0 "Stack initially should be of size zero") (enqueue q 1) (check-equal? (size q) 1 "Added one element to back of queue") (check-equal? (top q) 1 "Take a sneak peak at our first element") (dequeue q) (check-equal? (size 1) 0 "size should now be zero") (check-equal? (dequeue q) null "dequeue on empty queue returns null") )) #;(test-case "One Element queue --- Internal Test" (let ((q (make-queue))) (check-equal? (size q) 0 "queue initially should have size zero.") (enqueue q 3) (check-equal? (size q) 1 "Added one element.") (check-equal? (queue-back q) '(3) "Is the element in the back list?") (check-equal? (top s) 3 "Look at our one element.") (check-equal? (queue-front q) '(3) "Is the element in the front list?") (dequeue s) (check-equal? (queue-front q) '() "Is the data empty now?") )) (test-case "Multi Element queue --- Functional Test" (let ((q (make-queue)) (elts (list 8 6 7 5 3 0 9)) ) (check-equal? (size q) 0 "queue initially should have size zero.") (for ((i elts) (num (in-range 1 8))) (enqueue q i) (check-equal? (size q) num "Testing size.") (check-equal? (top q) i "Testing top with multiple additions.") ) (for ((i (reverse elts)) (num (reverse (stream->list (in-range 1 8))))) (check-equal? (top q) i "Testing top with multiple deletions") (dequeue q) (check-equal? (size q) (- num 1) "Testing size.") ) )) (test-case "Multi Element queue --- Ebb and Flow Test" (let ((q (make-queue)) (elts (list 8 6 7 5 3 0 9)) ) (check-equal? (size q) 0 "queue initially should have size zero.") (for ((i elts) (num (in-range 1 8))) (enqueue q i) (check-equal? (size q) num "Testing size, first flow.") (check-equal? (top q) i "Testing top with multiple additions.") ) (for ((i (reverse elts)) (num (reverse (stream->list (in-range 1 8))))) (check-equal? (top q) i "Testing top with multiple deletions") (dequeue q) (check-equal? (size q) (- num 1) "Testing size, first ebb.") ) (for ((i elts) (num (in-range 1 8))) (enqueue q i) (check-equal? (size q) num "Testing size, second flow.") (check-equal? (top q) i "Testing top with multiple additions.") ) (for ((i (reverse elts)) (num (reverse (stream->list (in-range 1 8))))) (check-equal? (top q) i "Testing top with multiple deletions") (dequeue q) (check-equal? (size q) (- num 1) "Testing size, second ebb.") ) )) (test-case "Multi Element queue --- Internal Test" (let ((q (make-queue)) (elts (list 5 8 8 2 3 0 0)) (tmp null) ) (for ((i elts) (num (in-range 1 8))) (enqueue q i) (check-equal? (size q) num "Testing size, second flow.") (set! tmp (cons i tmp)) ; "push" element to a list (check-equal? (queue-front q) tmp "Queue data is in correct form.") ) )) ) </code></pre> <p>When I run this code, I get a pretty straightforward error in one of your test cases.</p> <p>More generally, I'm taken aback that you would write this much test code without running it :). I would personally have written one small test case and then tried it out, rather than doing all of that work before discovering a more fundamental problem. I admire your tenacity, but I think you need a bit more paranoia :)</p> <p>Let me know if you have more trouble.</p> <p>EDIT: splitting into two files, per your request.</p> <p>File 1: queue.rkt</p> <pre><code>(module queue racket (provide make-queue enqueue dequeue top size) (struct queue (front back size) #:mutable #:transparent) (define (make-queue) (queue null null 0)) (define (enqueue q elt) (set-queue-back! q (cons elt (queue-back q))) (set-queue-size! q (+ (queue-size q) 1))) (define (dequeue q) (cond ((eq? (queue-size q) 0) null) ((null? (queue-front q)) (begin (set-queue-front! q (cdr (reverse (queue-back q)))) (set-queue-back! q null) (set-queue-size! q (- (queue-size q) 1)))) (else (begin (set-queue-front! q (cdr (queue-front q))) (set-queue-size! q (- (queue-size q) 1)))))) (define (top q) (cond ((eq? (queue-size q) 0) null) ((null? (queue-front q)) (last (queue-back q))) (else (car (queue-front q))))) (define (size q) (queue-size q)) ) </code></pre> <p>File 2: queue-tests.rkt, in the same dir:</p> <pre><code>(module test-queue racket (require "queue.rkt" rackunit) (test-case "Initial Queue Properties" (let ((q (make-queue))) (check-equal? (size q) 0 "Queue initially should have size zero.") (check-equal? (dequeue q) null "Dequeue on an empty queue returns null") (check-equal? (size q) 0 "Dequeue on empty queue leaves size as zero") )) (test-case "One Element queue ---- Functional test" (let ((q (make-queue))) (check-equal? (size q) 0 "Stack initially should be of size zero") (enqueue q 1) (check-equal? (size q) 1 "Added one element to back of queue") (check-equal? (top q) 1 "Take a sneak peak at our first element") (dequeue q) (check-equal? (size 1) 0 "size should now be zero") (check-equal? (dequeue q) null "dequeue on empty queue returns null") )) (test-case "One Element queue --- Internal Test" (let ((q (make-queue))) (check-equal? (size q) 0 "queue initially should have size zero.") (enqueue q 3) (check-equal? (size q) 1 "Added one element.") (check-equal? (queue-back q) '(3) "Is the element in the back list?") (check-equal? (top s) 3 "Look at our one element.") (check-equal? (queue-front q) '(3) "Is the element in the front list?") (dequeue s) (check-equal? (queue-front q) '() "Is the data empty now?") )) (test-case "Multi Element queue --- Functional Test" (let ((q (make-queue)) (elts (list 8 6 7 5 3 0 9)) ) (check-equal? (size q) 0 "queue initially should have size zero.") (for ((i elts) (num (in-range 1 8))) (enqueue q i) (check-equal? (size q) num "Testing size.") (check-equal? (top q) i "Testing top with multiple additions.") ) (for ((i (reverse elts)) (num (reverse (stream->list (in-range 1 8))))) (check-equal? (top q) i "Testing top with multiple deletions") (dequeue q) (check-equal? (size q) (- num 1) "Testing size.") ) )) (test-case "Multi Element queue --- Ebb and Flow Test" (let ((q (make-queue)) (elts (list 8 6 7 5 3 0 9)) ) (check-equal? (size q) 0 "queue initially should have size zero.") (for ((i elts) (num (in-range 1 8))) (enqueue q i) (check-equal? (size q) num "Testing size, first flow.") (check-equal? (top q) i "Testing top with multiple additions.") ) (for ((i (reverse elts)) (num (reverse (stream->list (in-range 1 8))))) (check-equal? (top q) i "Testing top with multiple deletions") (dequeue q) (check-equal? (size q) (- num 1) "Testing size, first ebb.") ) (for ((i elts) (num (in-range 1 8))) (enqueue q i) (check-equal? (size q) num "Testing size, second flow.") (check-equal? (top q) i "Testing top with multiple additions.") ) (for ((i (reverse elts)) (num (reverse (stream->list (in-range 1 8))))) (check-equal? (top q) i "Testing top with multiple deletions") (dequeue q) (check-equal? (size q) (- num 1) "Testing size, second ebb.") ) )) (test-case "Multi Element queue --- Internal Test" (let ((q (make-queue)) (elts (list 5 8 8 2 3 0 0)) (tmp null) ) (for ((i elts) (num (in-range 1 8))) (enqueue q i) (check-equal? (size q) num "Testing size, second flow.") (set! tmp (cons i tmp)) ; "push" element to a list (check-equal? (queue-front q) tmp "Queue data is in correct form.") ) ))) </code></pre>

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