Meroon is a CLOS-like object-oriented extension to Scheme written by Christian Queinnec, Professor Emeritus of the Sorbonne University, previously known as Paris VI.

Meroon has very specific design goals: single inheritance for fast access to object fields; generic functions with multi-methods (multiple dispatch); a compile-time meta-object-protocol (Meroon is written in Meroon, and its behavior can be modified at the time a program using it is compiled or loaded); fields can be declared mutable, immutable, or maybe-uninitialized, or they can have an initializer; so-called "poly-field"s can have a variable number of elements; special macros simplify the construction of objects (instantiate, co-instantiate, with-co-instantiation, duplicate, modify, instantiate-from).

Christian asked me to take over the maintenance of Meroon, and I agreed. I have some limited goals for Meroon (although it's not clear that I have the skills to implement them all):

• First, I do not want my modifications to interfere with using Meroon on various Scheme systems.
• With the previous goal in mind, I'd like to simplify the implementation of Meroon. I'd like to remove support for old, non-R[45]RS, systems, and for various experimental dispatch mechanisms.
• I have changed Meroon to use fixnum-specific operations fx+, fx-, ..., as specified in R6RS and implemented in various Schemes.
• Meroon has been integrated closely with Gambit. A Meroon object is a specially-tagged Gambit object; testing class membership, field access, etc., are fast.
• Long-term, I'd like to move Meroon from using define-macro macros to using hygienic macros. I'd also like to divide Meroon into specific layers of alternating "function definitions, macro definitions, function definitions, etc." where each layer can use all the previous layers. Right now Meroon is built by reading and evaluating each form in order (so each form is its own layer). As Meroon's documentation notes, the with-access macro is "not accurate" (at times it is incorrect); using a hygienic macro system would allow with-access to use a true code-walker.
• The documentation could be improved (and I don't believe I have all the source for the documentation).
• Meroon is not written with modules (which I take to mean name controls) in mind; that could be improved.

So I'm distributing Meroon in its current form. The source tarball contains a script make_meroon that builds Meroon for Gambit on Unix-like systems (Linux, *BSD, Mac OS X, etc.). Gambit-specific versions of Meroon source files are given the extension .gsc instead of .scm, so it should be possible to build Meroon in Christian's original way for other Scheme systems. The software is distributed under the Lisp Lesser General Public License (LLGPL), version 2.1, to which Christian has agreed and which I feel is necessary because Meroon generates code from class definitions, etc.

I'm also soliciting help for various aspects of improving Meroon according to the criteria above, or other criteria as you see fit.

If you have questions or suggestions about how to improve Meroon, please send me e-mail.

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