Scheme programming. If someone could help me out with these two functions that w

Question

Scheme programming. If someone could help me out with these two functions that would be great.

Write a function, infix->prefix, which takes an infix arithmetic expression and returns the corresponding prefix expression. > (infix->prefix 42) 42 > (infix->prefix '(1 + 2)) (+ 1 2) > (infix->prefix '(1 + (2 * 8))) (+ 1 (* 2 8)) > (infix->prefix '((((2 + 3) * 2)/5) + (17 - 1)) (+ (/(* (+ 2 3) 2) 5) (- 17 1)) Define a function iota-iota that takes an integer i as its argument and returns a list of pairs of integers such that > (iota-iota 1) ((1. 1)) > (iota-iota 2) ((1. 1) (1. 2) (2. 1) (2 .2)) > (iota-iota 3) ((1. 1) (1. 2) (1 .3) (2. 1) (2 .2) (2. 3) (3 .1) (3. 2) (3. 3))

Explanation / Answer

(load "test.scm")
(load "homework2.scm")

(test (infix->prefix 42) 42)
(test (infix->prefix '(1 + 2)) '(+ 1 2))
(test (infix->prefix '(1 + (2 * 8))) '(+ 1 (* 2 8)))
(test (infix->prefix '((((2 + 3) * 2) / 5) + (17 - 1)))
      '(+ (/ (* (+ 2 3) 2) 5) (- 17 1)))

(test (iota-iota 0) '())
(test (iota-iota 1) '((1 1)))
(test (iota-iota 2) '((1 1) (1 2) (2 1) (2 2)))
(test (iota-iota 3) '((1 1) (1 2) (1 3) (2 1) (2 2) (2 3) (3 1) (3 2) (3 3)))

homework2.scm

;; Additional Problem 2
(define infix->prefix
(lambda (ls)
    (cond
     ((null? ls) '())
     ((number? ls) ls)
     ((and (pair? (car ls)) (pair? (caddr ls)))
      (cons (cadr ls) (cons (infix->prefix (car ls))(list (infix->prefix (caddr ls))))))
     ((pair? (car ls))
      (cons (cadr ls) (cons (infix->prefix (car ls)) (list (caddr ls)))))
     ((pair? (caddr ls))
      (cons (cadr ls) (cons (car ls) (list (infix->prefix (caddr ls))))))
     (else
      (cons (cadr ls) (cons (car ls) (list (caddr ls))))))))

;; Additional Problem 3
(define iota-iota
(lambda (n)
    (letrec ((loop
          (lambda (x y acc)
       (cond
       ((> x n) acc)
       ((> y n) (loop (add1 x) 1 acc))
       (else (loop x (add1 y) (append acc (list (list x y)))))))))
      (loop 1 1 '()))))

test.scm

(define test
(lambda (actual expected)
    (if (equal? actual expected) (displayln "pass") (displayln "fail"))))

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