<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type"> </head> <body bgcolor="#ffffff" text="#000000"> Eli Barzilay wrote at 07/10/2011 02:25 AM: <blockquote cite="mid:19993.17861.22732.798523@winooski.ccs.neu.edu" type="cite"> <blockquote type="cite"> <pre wrap="">it should work as you originally expected, or it should raise an error to complain about an internal "define" referencing itself like that and ignoring the pre-existing binding from the argument. </pre> </blockquote> <pre wrap=""> An error would be nice, but racket never did that. Same as `letrec'. </pre> </blockquote> So, I think that this should be an error, given the current semantics: (define X X) Maybe that's an extremely simple example of a more general error of attempting to evaluate an uninitialized variable.  At least, I think that the ones that can be proven statically to always be uninitialized references should be compile errors.  Or is there a good reason for the compiler to be more liberal? Separately, I also think that maybe the following should be an error, since someone doing this with internal-"define" instead of "let" is most likely a student, and a student probably doesn't mean to do this: (define (foo name)   (define name ...)   ...) <div class="moz-signature">-- <a class="moz-txt-link-freetext" href="http://www.neilvandyke.org/">http://www.neilvandyke.org/</a> </div> </body> </html>