Re: Guile REPL Server

[David Kastrup]

Jonas Hahnfeld via LilyPond user discussion <lilypond-user@gnu.org>
writes:

> On Tue, 2022-05-17 at 23:28 +0200, David Kastrup wrote:
>> Jonas Hahnfeld via LilyPond user discussion <lilypond-user@gnu.org>
>> writes:
>> 
>> > On Tue, 2022-05-17 at 09:57 +0200, Jean Abou Samra wrote:
>> > > Le 17/05/2022 à 00:29, Hendursaga a écrit :
>> > > > I'm trying to start a REPL server[1] inside LilyPond's Guile
>> > > interpreter, but I can't get it to even load readline support.
>> > > 
>> > > Readline support is an optional feature in Guile. It looks like
>> > > out new infrastructure for building binaries compiles Guile without
>> > > it. We may or may not want to do it (Readline is an extra dependency);
>> > > CCing Jonas on this matter.
>> > 
>> > Right, this is intentional. I don't find it convincing that the
>> > official binaries should be bigger for everybody to enable an optional
>> > feature (readline support) in a dependency (Guile) that only a very
>> > tiny fraction might ever try to use...
>> 
>> Personally, I'd rather have it.  The tiny fraction that will want
>> readline support will want it for running scheme-sandbox or other forms
>> of REPL.  It greatly increases the friendliness of playing around with
>> Scheme stuff in the manner the manual suggests, and the people playing
>> around with Scheme stuff are the most likely candidates for becoming
>> future contributors.
>
> As I just replied in my other message, the REPL itself works fine.

"[readline] greatly increases the friendliness of playing around with
Scheme stuff in the manner the manual suggests, ..."

>
>> We don't make the "Extending LilyPond" guide optional for a reason, and
>> it starts off right away with
>> 
>>     1.1.1 Scheme sandbox
>>     --------------------
>> 
>>     The LilyPond installation includes the Guile implementation of Scheme.
>>     On most systems you can experiment in a Scheme sandbox by opening a
>>     terminal window and typing ‘guile’.  On some systems, notably Windows,
>>     you may need to set the environment variable ‘GUILE_LOAD_PATH’ to the
>>     directory ‘../usr/share/guile/1.8’ in the LilyPond installation.  For
>>     the full path to this directory see *note (lilypond-learning)Other
>>     sources of information::.  Alternatively, Windows users may simply
>>     choose ‘Run’ from the Start menu and enter ‘guile’.
>
> This paragraph is outdated and I'm working towards not shipping the
> separate guile executable with the official binaries.

Probably by recoding lilypond-invoke-editor in a different language?

> I'll update the documentation afterwards to mention that it can be
> installed on many Linux systems, but is / will not be included in the
> binaries.

Does this have to do with byte-compilation?
>
>>        However, a hands-on Scheme sandbox with all of LilyPond loaded is
>>     available with this command line:
>>          lilypond scheme-sandbox
>> 
>>     Once the sandbox is running, you will receive a guile prompt:
>> 
>>          guile>
>> 
>>        You can enter Scheme expressions at this prompt to experiment with
>>     Scheme.
>
> Up to here, this works fine (even if the prompt looks a bit different
> now).
>
>>     If you want to be able to use the GNU readline library for
>>     nicer editing of the Scheme command line, check the file
>>     ‘ly/scheme-sandbox.ly’ for more information.  If you already have
>>     enabled the readline library for your interactive Guile sessions outside
>>     of LilyPond, this should work in the sandbox as well.
>
> What does "nicer editing" mean here? If that is an optional feature to
> an already optional REPL, I'm even more inclined to not include it.

More or less "any editing at all" apart from backspacing over text
before pressing RET.

-- 
David Kastrup