Ok, I quite agree with you. Indeed my little tests did not show any significant difference. Laurent <div class="gmail_quote">On Fri, Nov 20, 2009 at 17:32, Carl Eastlund <<a href="mailto:carl.eastlund@gmail.com">carl.eastlund@gmail.com</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><div></div><div class="h5">On Fri, Nov 20, 2009 at 11:25 AM, Laurent <<a href="mailto:laurent.orseau@gmail.com">laurent.orseau@gmail.com</a>> wrote: > > On Fri, Nov 20, 2009 at 17:14, Carl Eastlund <<a href="mailto:carl.eastlund@gmail.com">carl.eastlund@gmail.com</a>> > wrote: >> >> On Fri, Nov 20, 2009 at 10:55 AM, Joe Marshall <<a href="mailto:jmarshall@alum.mit.edu">jmarshall@alum.mit.edu</a>> >> wrote: >> > On Fri, Nov 20, 2009 at 5:57 AM, Laurent <<a href="mailto:laurent.orseau@gmail.com">laurent.orseau@gmail.com</a>> >> > wrote: >> >> >> >> I have the following (simplified) code : >> >> >> >> (define (f1 x) >> >> (let ([y (foo x)]) >> >> (bar x y y) >> >> (plop y x y) >> >> (baz x y))) >> >> >> >> (define (f2 x) >> >> (let ([y (foo x)]) >> >> (baz x y))) >> > >> > (define (wrapper receiver) >> > (lambda (x) >> > (let ((y (foo x))) >> > (receiver x y) >> > (baz x y)))) >> > >> > (define f1 >> > (wrapper >> > (lambda (x y) >> > (bar x y y) >> > (plop y x y) ))) >> > >> > (define f2 >> > (wrapper >> > (lambda (x y) #f))) >> >> Oops. Joe, of course, has the best solution. No need for "macrology" >> when "functionality" does the job. Pardon the puns. > > But this introduces a (little?) run-time cost, doesn't it? </div></div>Two responses. One, code clarity is almost always more important than tiny runtime costs. Two, no it doesn't, as long as the compiler is even halfway intelligent about inlining and constant propagation. Trust the compiler. If it's good, it's often smarter about optimizing your code than you are. If it's bad, your code is never going to run fast anyway. --Carl </blockquote></div>