[racket] I just can't understand readtables

From: Danny Yoo (dyoo at hashcollision.org)
Date: Mon Apr 29 17:02:34 EDT 2013

On Mon, Apr 29, 2013 at 2:12 PM, Tomás Coiro <tomcoiro at hotmail.com> wrote:
> Thanks for that Danny :)
> I'll try to do that.
> Although I think that readtables documentations aren't understandable.
> I mean, searching on Google I can find 3 or 4 questions about them and no
> one seems to understand them.

I'm pretty sure someone has to understand them on this list...  :P

Here are some entries on Stack Overflow that may help:


For your situation, if you're making your own language, you've got to
make sure that the dynamic extent in which you're customizing the
reader is wrapping around the use of read or read-syntax that's being
done when your programs are being parsed.  If you can point us to code
that you've tried, that may help to identify what went wrong in the
first place.

In terms of something like the BF tutorial, it would be somewhere around here:


at the point where we tell Racket how to read our program into syntax.
 You've got to make sure the module reader you've coded up will is
running read and read-syntax under your customized reader at this
point, as the program is being read: otherwise, your customized reader
comes too late: the program's already been read and parsed.

Posted on the users mailing list.