On 24-02-2023 16:45, Ludovic Courtès wrote:
>>> Adding #lang support in Guile would be nice.  As discussed on IRC, it
>>> can be experimented with in a WIP branch.
>> Have you seen my messages on how the "#lang" construct is problematic
>> for some languages, and how alternatives like "[comment delimiter] -*-
>> stuff: scheme/ecmascript/... -*- [comment delimiter]" appear to be
>> equally simple (*) and not have any downsides (**).
>>
>> (*) The port encoding detection supports "-*- coding: whatever -*-",
>> presumably that functionality could be reused.
>>
>> (**) For compatibility with Racket, it's not like we couldn't
>> implement both "#lang" and "-*- stuff: language -*-".
> I haven’t seen your messages yet, I just wanted to express support of
> the general idea.  For years, we have discussed #lang support; I know
> Andy is enthusiastic about it, and while I was initially reluctant, I’ve
> come to appreciate the idea.
> 
> What you point out is worth considering, but note that Guile already
> supports #!r6rs for instance.

While I initially thought that #!r6rs was problematic, it was pointed 
out to me that #!r6rs is actually in the R6RS (unlike #lang, and even if 
#lang was in the R6RS, it isn't in the de-jure or de-factor standards of 
many other languages).

As such, #!r6rs is a different (unproblematic) situation compared to 
#lang -- #lang is not the same as #!r6rs from a compatibility perspective.

Greetings,
Maxime.