Racket Scheme nested define

Question

My target is to write method which by given х and n calculate the sum:

S = 1 + x/1! + x2/2! + ... + xn/n!

My code:

#lang racket
(define (func n)
  (define (n1! f)
    (if (= f 0) 1
        (* f (n1! (- f 1)))))
  (define (iter i res)
    (if (= i n) (+ 1 res)
       (iter (+ i 1) (/ i (n1! i))))))
(func 3)

There is error which I do not understand. It says:

begin (possibly implicit): no expression after a sequence of internal definitions in:
  (begin (define (n1! f) (if (= f 0) 1 (* f (n1! (- f 1))))) (define (iter i res) (if (= i n) (+ 1 res) (iter (+ i 1) (/ i (n1! i))))))
  (define (n1! f) (if (= f 0) 1 (* f (n1! (- f 1)))))
  (define (iter i res) (if (= i n) (+ 1 res) (iter (+ i 1) (/ i (n1! i)))))

What I do wrong?

Answer 1

You need to add an expression after the two defines, so that func will actually do something. Currently your code is equivalent to (define (func n)) .

Your code is this

(define (func n)
  (define (n1! f)
    (if (= f 0) 1
        (* f (n1! (- f 1)))))
  (define (iter i res)
    (if (= i n) (+ 1 res)
       (iter (+ i 1) (/ i (n1! i))))))

you need to do this

(define (func n)
  (define (n1! f)
    (if (= f 0) 1
        (* f (n1! (- f 1)))))
  (define (iter i res)
    (if (= i n) (+ 1 res)
       (iter (+ i 1) (/ i (n1! i)))))
  (iter n 0))