I got “scheme application not a procedure” in the last recursive calling of a function

Question

so here is the code:

(define (time-prime-test n)
  (newline)
  (display n)
  (start-prime-test n (runtime)))

(define (start-prime-test n start-time)
  (if (         


        

Answer 1

  ((time-prime-test n)
   (search-for-primes (+ n 1) m))

This will try to apply the result of time-prime-test as a procedure. time-prime-test doesn't return a procedure. Use begin:

  (begin
   (time-prime-test n)
   (search-for-primes (+ n 1) m))