CS 3520 Homework 6   - Due October 17

Exercise 6.1, Set! finger exercises

• Complete the following Scheme definition (replace the "..."):

            (define (ex1 v1 v2)
             (let ([f ...])
               (begin
                 (f v1)
                 (f v2))))

  so that the value of (ex1 n m) is (list m n) for any integers n and m. The catch is that neither v1 nor v2 may appear in anywhere within the expression replacing "...".

• Complete the following Scheme definition (replace the "..."):

            (define (ex2 v1 v2)
             (let ([mk ...])
               (let ([f (mk)]
                     [g (mk)])
                 (begin
                  (f (list v1))
                  (g (list v2))
                  (g '())))))

  so that the value of (ex2 n m) is (list n m) for any integers n and m. As before, neither v1 nor v2 may appear in anywhere within the expression replacing "...".

• Complete the following Scheme definition (replace the "..."):

            (define (ex3 v1 v2)
             (let ([mk ...])
               (let ([f (mk)]
                     [g (mk)])
                 (begin
                  (g (list v1))
                  (f (list v2))
                  (g '())))))

  so that the value of (ex3 n m) is (list n) for any integers n and m. As always, neither v1 nor v2 may appear in anywhere within the expression replacing "...".

• Complete the following Scheme definition (replace the "..."):

            (define (ex4 v1 v2 v3 v4)
             (let ([mk ...])
               (let ([f (mk)]
                     [g (mk)])
                 (begin
                  (f (list v1) (list v2))
                  (g (list v3) (list v4))
                  (list (f '() '()) (g '() '()))))))

  so that the value of (ex4 n m p q) is (list (list n m q) (list m q p)) for any integers n, m, p, and q. Of course, v1, v2, v3, or v4 may not appear in anywhere within the expression replacing "...".