Grails 1.3.1 dependency resolution

After upgrading Grails to 1.3.1 from 1.2.2, I repeatedly received "UNRESOLVED DEPENDENCIES" errors. After an inordinate amount of troubleshooting, I stumbled upon the sole archived message on the Internet that recommended deleting (or renaming) the %USER_HOME%\.ivy2 directory. Sure enough, this worked like a charm, so I post the resolution here for posterity. It seems there were some transitive dependencies that weren't getting sorted out. It's all good now.

The Light Bulb Is Not Yet On

I have reset on going through Essentials of Programming Languages, and struggling my way through learning Scheme. I wrote a working answer (at least as tested) for a problem in the second chapter, but I feel like I happened upon it through test-driven development. I suppose in some ways that's a good thing, but I can say that it is not a terribly comfortable feeling to write some code but not really grok what it's doing. Anyway, here is the paraphrased problem, and my solution (test cases included):

Exercise 2.2.9, #3. (car&cdr2 s slst errvalue) generates a procedure composition that, when evaluated, produces the code for a procedure that takes a list with the same structure as slst and returns the value in the same position as the leftmost occurrence of s in slst. If s does not occur in slst, then errvalue is returned.

(define (contains? s los)
  (if (null? los)
      #f
      (if (symbol? (car los))
          (if (eq? s (car los))
              #t
              (contains? s (cdr los)))
          (if (contains? s (car los))
              #t
              (contains? s (cdr los))))))
              
(define (car&cdr2 s slst errvalue)
  (if (contains? s slst)
      (car&cdr2-help s slst 'car)
      errvalue))

(define (car&cdr2-help s slst lst)
  (if (symbol? (car slst))
      (if (eq? s (car slst))
          lst
          (list 'compose lst (car&cdr2-help s (cdr slst) 'cdr)))
      (if (contains? s (car slst))
          (list 'compose 'car (car&cdr2-help s (car slst) 'cdr))
          (list 'compose lst (car&cdr2-help s (cdr slst) 'cdr)))))

Here are the tests (schemeunit):

(define-test-suite 2.2.9
  (test-case "3."
             (check equal?
                    (car&cdr2 'a '() 'fail)
                    'fail)
             (check equal?
                    (car&cdr2 'a '(a) 'fail)
                    'car)
             (check equal?
                    (car&cdr2 'a '(b) 'fail)
                    'fail)
             (check equal?
                    (car&cdr2 'a '(a b) 'fail)
                    'car)
             (check equal?
                    (car&cdr2 'b '(a b) 'fail)
                    '(compose car cdr))
             (check equal? 
                    (car&cdr2 'c '(a b c) 'fail)
                    '(compose car (compose cdr cdr)))
             (check equal? 
                    (car&cdr2 'd '(a (b c) d) 'fail)
                    '(compose car (compose cdr cdr)))
             (check equal?
                    (car&cdr2 'dog '(cat lion (fish dog) pig) 'fail)
                    '(compose car (compose cdr (compose car (compose cdr cdr)))))
             (check equal? 
                    (car&cdr2 'c '((a b) c) 'fail)
                    '(compose car cdr))))

Any Schemers care to give me pointers? I sure could use the help.