Re: [Kawa-commonlisp-dev] [GSoC] Destructuring bind

[Charles Turner]

On 31 July 2012 08:19, Helmut Eller <address@hidden> wrote:
> Remember that macros are expanded at compile time and the compiled code
> doesn't need the macro definition.  SBCL is a meta-circular
> implementation, i.e. the SBCL compiler is compiled by another CL
> compiler. That makes some things easier.  The other compiler already has
> a working DESTRUCTURING-BIND so they are free to use it in the SBCL
> source code.

Ah, makes sense now. Thanks.

> Doing that manually isn't that hard:

Good idea! I'll eventually get the hang of this... :)

> Also CMUCL's version of parse-defmacro-lambda-list uses no
> DESTRUCTURING-BIND at all:
> http://common-lisp.net/gitweb?p=projects/cmucl/cmucl.git;a=blob_plain;f=src/code/defmacro.lisp;hb=HEAD

Hm, that does seem a lot simpler (lot of common code of course). But
I've committed to the SBCL implementation now, and I've had no further
missing features, other than a couple of TAGBODY things again, but I'm
avoiding for now using exit continuations.

I have now finished importing the bulk of the code required for
PARSE-DEFMACRO. It's not yet working, loads of bugs probably to be
worked out, but it's at least being eaten by the compiler. I've
uploaded it to my repository now, but I expect to be spending quite of
a lot of time getting it to work correctly:

http://chturner.com/kawa/trunk/gnu/commonlisp/lisp/defmacro.lisp

> Rewriting everything in Java is an option, but IHMO it's
> more elegant to write as much in Lisp as possible.

I agree.

Thanks,
Charles.