Path: utzoo!attcan!uunet!yale!krulwich-bruce
From: krulwich-bruce@CS.YALE.EDU (Bruce Krulwich)
Newsgroups: comp.lang.scheme
Subject: Re: Macros; lexcial scope
Message-ID: <30160@yale-celray.yale.UUCP>
Date: 26 May 88 14:53:24 GMT
References: <8805251659.AA00682@tub.UUCP>
Sender: root@yale.UUCP
Reply-To: krulwich-bruce@CS.YALE.EDU (Bruce Krulwich)
Organization: Yale University Computer Science Dept, New Haven CT  06520-2158
Lines: 29

In article <8805251659.AA00682@tub.UUCP> net@TUB.BITNET (Oliver Laumann)
writes:
>Consider the following example:
>   (define x 1)
>   (define-macro (m) x)
>   (let ((x 2))
>     (m))
>Would you expect that (m) evaluates to 1 or to 2?  In both Common Lisp
>(using a different syntax, of course) and C-Scheme, (m) returns 1 in the
>example above.  Thus, it looks as if the first time the macro body is
>evaluated, the evaluation takes place in the lexical scope of the
>define-macro.

Rather, that the macro is evaluated in the lexical scope in which it was 
defined, just like regular functions.

>Now consider a slighly more complex example:
>   (define x 1)
>   (let ((x 2))
>     (define-macro (m) x)
>     (let ((x 3))
>       (m)))
>In both Common Lisp and C-Scheme, this evaluates to 1.

T's DEFINE-SYNTAX does what you want in both of these cases, evaluating to 1
in the first case and 2 in the second case.  


Bruce Krulwich