Thank you both, that is exactly what I need! With the syntax-id-rules and I also use a (certainly common) macro pattern, which I just learned today (from planet btw) to apply it a list of values : (define-syntax-rule (define-my-ids stx ...) (begin (define-my-id stx) ...)) This last one is the kind of macro I'd be glad to find in the PLT docs. Thanks again, Laurent <div class="gmail_quote">On Sat, Sep 26, 2009 at 20:49, Jon Rafkind <<a href="mailto:rafkind@cs.utah.edu">rafkind@cs.utah.edu</a>> wrote: <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><div class="im">Laurent wrote: <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> Hi all, I timidly require your help on a simple macro I've been trying to do for some time now. I usually prefer to do things myself, but I'm stuck. Here's the thing : I have an identifier and I want to generate an identifier based on it but with a different name. (in fact I have lots of identifiers) for example : (define-my-id trout) would generate the macro identifier my-id-trout that expands to, say, (display "trout"). My concern is about using in the program an identifier that is not defined explicitly in the program file. This should be possible though, since this is partly what define-struct does, I suppose. </blockquote> </div> Maybe something like this is what you are after #lang scheme (define-syntax (define-my-id stx) (syntax-case stx () [(_ id) (with-syntax ([my-id (datum->syntax #'id<div class="im"> (string->symbol (string-append "my-id-" (symbol->string </div> (syntax->datum #'id)))) #'id)]) #'(define-syntax-rule (my-id) (display 'id)))])) (define-my-id foo) (my-id-foo) ;; end In general if you want to create new identifiers you should use syntax-case and with-syntax. with-syntax takes some syntax and binds it to an identifier that can be used in a template and you are free to generate the syntax that it binds. define-syntax-rule is just a shorthand for (define-syntax foo (syntax-rules ...)).<div class="im"> <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> With eval and quasi-quoting I can easily generate an approximation with a lambda'd form but Scheme won't let me use identifiers that are not explicitly defined (it works in the REPL though): (define (define-my-id id) (eval `(define ,(string->symbol (string-append "my-id-" (symbol->string id))) (lambda () (display ,(symbol->string id)))))) I also know that syntax-id-rules can generate expanding identifiers, but I can't use string-append et al in macros to generate a new id... </blockquote> </div> If you want to use the result of the above macro as 'my-id-foo' instead of '(my-id-foo)' then you can use syntax-id-rules, but using eval is usually not the right way to generate new identifiers.<div class="im"> <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> Also, where can I find some simple macro samples, other than in the guide ? </blockquote> </div> I guess you can look at code on planet or in the collects directory of the PLT tree, but I'm beginning to think a more expansive explanation section of the docs would be useful. Something like extremely detailed comments about "real code". </blockquote></div>