3.3 Solution for Exercise 13

An expression is represented by a function; a clause containing two expressions can be represented by a pair of functions.

(define-syntax-rule (my-cond-v0 [question-expr answer-expr] ...)

(my-cond-v0-fun

(list

(cons    ; bleh, I know, improper use of cons

(lambda () question-expr)

(lambda () answer-expr))

...)))

(define (my-cond-v0-fun clauses)

(if (pair? clauses)

(let ([question-thunk (car (car clauses))]

[answer-thunk (cdr (car clauses))])

(if (question-thunk)

(answer-thunk)

(my-cond-v0-fun (cdr clauses))))

(void)))