You didn't define the datatype. Shriram
On Mon, Sep 13, 2010 at 7:12 AM, wooks . <woo...@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. > > _________________________________________________ > For list-related administrative tasks: > http://lists.racket-lang.org/listinfo/users > _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
