[racket] PLAI An inauspicious start

From: wooks . (wookiz at hotmail.com)
Date: Mon Sep 13 07:12:11 EDT 2010

Trying out the first example in the book

#lang plai
(define (parse sexp)
    [(number? sexp) (num sexp)]
    [(list? sexp)
     (case (first sexp)
       [(+) (add (parse (second sexp))
                 (parse (third sexp)))]
       [(-) (sub (parse (second sexp))
                 (parse (third sexp)))])]))

I get 

<unsaved editor>:4:21: expand: unbound identifier in module in: num

FWIW I have installed the patch on the books webpage and am running Racket 5.01 on Ubuntu.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.racket-lang.org/users/archive/attachments/20100913/4207d08b/attachment.html>

Posted on the users mailing list.