Thanks Matthias and Sam, the macro expansion now works as I intended, with the following change: (define-syntax-rule (with-monad (<unit-f> <bind-f>) <body>) (let ((u <unit-f>) (b <bind-f>)) (syntax-parameterize ([bind (make-rename-transformer #'b)]) (syntax-parameterize ([unit (make-rename-transformer #'u)]) <body>)))) <div class="gmail_quote">2011/7/19 Sam Tobin-Hochstadt <<a href="mailto:samth@ccs.neu.edu">samth@ccs.neu.edu</a>> <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"> <div class="im">On Tue, Jul 19, 2011 at 2:06 PM, Ismael Figueroa Palet <<a href="mailto:ifigueroap@gmail.com">ifigueroap@gmail.com</a>> wrote: > Hi all, I'm trying to implement some simple macros to use monads in racket > using a Haskell-like do notation. I have the following macros, and my > problem is that I want the do macro to capture the bind identifier created > by with-monad, and in each recursive step of the do macro expansion keep the > same identifier. I don't know it is possible, I tried using (with-syntax > ((bind (datum->syntax 'bind) ))) but it doesn't work. </div>I think the right solution here is to use syntax parameters [1]. This blog post by Eli provides a good intro: <a href="http://blog.racket-lang.org/2008/02/dirty-looking-hygiene.html" target="_blank">http://blog.racket-lang.org/2008/02/dirty-looking-hygiene.html</a> [1] <a href="http://docs.racket-lang.org/reference/stxparam.html" target="_blank">http://docs.racket-lang.org/reference/stxparam.html</a> -- sam th <a href="mailto:samth@ccs.neu.edu">samth@ccs.neu.edu</a> </blockquote></div> -- Ismael