[racket] PLAI An inauspicious start

You didn't define the datatype.

Shriram

On Mon, Sep 13, 2010 at 7:12 AM, wooks . <wookiz at hotmail.com> wrote:
> Trying out the first example in the book
>
> #lang plai
> (define (parse sexp)
>   (cond
>     [(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.
>
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