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From: steve g <Sgonedes1977@gmail.com>
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Subject: Re: implementing scheme - implementing macros
References: <110hst1$2gjgb$1@dont-email.me>
Date: Tue, 16 Jun 2026 21:50:26 -0400
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Mario Rosell <mario@mariorosell.es> writes:

> [ Repost from Reddit. r/lisp: https://t.ly/Fldzk ]
>
> Hello everyone.
>
> I am making a Scheme R5RS implementation and it is going pretty well.
>
> I am trying implement macros, and don't really know how to implement them.
> Scheme has a pretty complex macro system, so for now I am trying to
> implement defmacro and then implement define-syntax, syntax-case, etc.
>
> Any tips?


using eval is your friend.


the old emacs way was hard to read.

the emacs lisp info page: "

14.1 A Simple Example of a Macro
================================

Suppose we would like to define a Lisp construct to increment a variable
value, much like the ‘++’ operator in C.  We would like to write ‘(inc
x)’ and have the effect of ‘(setq x (1+ x))’.  Here's a macro definition
that does the job:

     (defmacro inc (var)
        (list 'setq var (list '1+ var)))

 "

you need to ``reevaluate'' the macro twice.

the commmon lisp was uses symbols like @ , .  etc..


hope this is helpful.