Question

Hello I am following the quick introduction to racket. In chapter 5 they propose that this code (which worked fine):

(define (four p)
  (define two-p (hc-append p p))
  (vc-append two-p two-p))

would tipically be written by using let, so I wrote my code:

#lang slideshow

(define (square n)
  (filled-rectangle n n))
(define (four p)
  (let ([two-p (hc-apppend p p)])
  (vc-append two-p two-p)))

but it doesn’t work.
The error message is:

expand: unbound identifier in module in: hc-apppend

Answer 1

Just checking: Did you remember

#lang slideshow

as the first line?

Also, count the number of p characters! It is hc-append. The error mentions hc-apppend: it should be hc-append.