<div dir="ltr">Thanks a lot, Matthew! That works!</div><div class="gmail_extra"> <div class="gmail_quote">On Tue, May 14, 2013 at 8:06 AM, Matthew Flatt <<a href="mailto:mflatt@cs.utah.edu" target="_blank">mflatt@cs.utah.edu</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi Alfred, See <a href="http://docs.racket-lang.org/guide/eval.html#(part._namespaces)" target="_blank">http://docs.racket-lang.org/guide/eval.html#(part._namespaces)</a> Matthew <div><div class="h5"> At Tue, 14 May 2013 07:01:51 -0400, Alfred Zhong wrote: > Hi Racket experts, > > I am reading SICP and trying this piece of code using Racke: > > (define (definition-value exp) > (if (symbol? (cadr exp)) > (caddr exp) > (make-lambda > (cdadr exp) ; formal parameters > (cddr exp) ; body > ) > ) > ) > > (define (make-lambda parameters body) > (cons 'lambda (cons parameters body)) > ) > > ( (eval (definition-value '(define (double x) (+ x x))) ) 10) > > In REPL, it return 20 with no problem. > > However, if I put it into a file and use racket command to run it (with > #lang scheme in the file) > > it complains: > compile: unbound identifier (and no #%app syntax transformer is bound) at: > lambda in: (lambda (x) (+ x x)) > > Do you have any idea what happened there? How can I solve this problem? > > Thanks, > Alfred </div></div>> ____________________ > Racket Users list: > <a href="http://lists.racket-lang.org/users" target="_blank">http://lists.racket-lang.org/users</a> </blockquote></div> </div>