OMeta for Scheme

By: on July 1, 2008

Speaking of OMeta/JS [old link:] and OMeta in general, I’ve implemented an OMeta for Scheme. Currently it runs in MzScheme, but it should be fairly portable, with dependencies only on a handful of commonly-implemented SRFIs. I intend to properly libraryise it — making it into a proper MzScheme module — and to port it to other schemes, most probably starting with SISC.

One interesting feature of this OMeta is that it implements the error-handling mechanisms suggested by Bryan Ford that I implemented previously in a packrat parsing library for Scheme. The packrat-based error-handling techniques seem to generalise fairly well to an OMeta setting.

* Browse the code here.
* Check it out with hg clone

I’m already using it as part of an experimental compiler: the reader, the parser.

Update: Switched from hosting the ometa-scheme code in Darcs to Mercurial.



  1. web design says:

    For you Lisp2 fans, a common lisp version has been posted to reddit previously:

  2. John Pallister says:


    Thanks for making your code available. I’m a Lisper interested in OMeta, so between your Scheme code and John Leuner’s Lisp port of the Squeak version (as mentioned above) I hope to get (a) my head around OMeta and (b) some Lisp code of my own that I understand.

    I like your mention of extra (any?) error handling stuff, and the fact that your code is 803 lines of Scheme vs. 3000+ lines of Lisp and 5000+ lines of JavaScript… 😉

    And now my question: I’ve downloaded the latest MzScheme, but it looks like your code won’t run in version 4 out of the box (not that I’ve used this particular box before).

    If I want to study your code interactively, would I be best advised to download a slightly earlier version of MzScheme? Or should I hang on for the next release?

    Thanks again,

    John :^P

  3. Thanks for this, very timely.

    I made it work with PLT scheme 4, more or less – using enter! in a command-line mzscheme, at least. (boot) works, (opt (parse-ometa “a ::= ‘a’ => true;”)) works, I haven’t figured out how to parse actual data. See darcs repo at;a=summary

  4. John Pallister says:

    Thanks for that Simon, I’ll grab the latest code and try again.


    John :^P

  5. tonyg says:

    John, Simon: Thanks for trying out the code — and thanks for the bug report. I’ve not yet upgraded to mzscheme 4, but will do so and integrate Simon’s patches ASAP.

  6. tonyg says:

    I’ve switched the repository from darcs to mercurial, and updated the links in the post above. I’ve also incorporated Simon’s fixes for MzScheme 4 — thanks, Simon!

    The situation now is that the default branch is the PLT 4 branch, and PLT 3 support is now legacy, and lives on a support branch.

Leave a Reply

Your email address will not be published.

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>