Subject: [bug#72994] [PATCH] gnu: emacs-julia-snail: Vendor julia libraries.

From: [email-masked]
Date: Mon, 16 Sep 2024 20:01:16 +0200

Hi Ludo,

On 2024-09-16 10:24, Ludovic Courtès wrote:
>> +                (copy-recursively (string-append (assoc-ref inputs 
>> "julia-tokenize")
>> +                                                 
>> "/share/julia/loadpath/Tokenize")
> 
> Use ‘search-input-directory’ rather than ‘assoc-ref’.

Will do!

> I’m not sure I understand.  For most programming languages (Python,
> etc.), we use propagated inputs like this.  How does that differ?
> 
> Normally we unbundle (“unvendor”?) libraries and this seems to go in 
> the
> opposite direction, right?

The idea is to make Guix more user-friendly.

I touched this only after I myself got bitten by the following:

I have guix home (with only a few packages--notably no julia (!) or 
gcc-toolchain
or anything like that in it),
and I have emacs set up with emacs-buffer-env and the following 
configuration:

   (setq buffer-env-script-name '("manifest.scm" ".envrc"))

In a julia project, manifest.scm contains:

   (specifications->manifest
     (list "julia"))

The idea is that emacs-bufferenv will automatically load that manifest 
when I
open a file in that directory within emacs--and then have julia-snail 
REPL
(including sending expression on point to the REPL) work.

Since the emacs julia-snail REPL integration needs to find the bounds of 
the expression,
it has to have a parser for the Julia language.

However, what happens now is that because I don't have julia-cstparser 
and julia-tokenize
in guix home, it won't work.

But from the standpoint of the profile I shouldn't have julia-cstparser 
and julia-tokenize
in my home profile since I don't personally directly use it (it's a 
requirement of emacs-julia-snail--I didn't even know what 
julia-cstparser is a few days ago :) ).

But nevermind that.  Even if I added julia-cstparser and julia-tokenize 
to my
guix home profile, it would NOT work.  The reason is because julia 
itself is not part of
the guix home profile, and the "julia" package would have a search-path 
specification that
would set some environment variables that julia needs to find 
julia-cstparser and
julia-tokenize.
Since the package is not there (in guix home) it won't set the 
variables.

The idea of this patch is that emacs will automatically set up whatever 
it needs to in order
to make the REPL work (including the finding of the boundaries of the 
current expression
that the emacs package needs for "send expression at point to REPL") 
without weird
dependencies bleeding explicitly into the user profile or into the local 
directory's manifest.

In my opinion, the user should not need to be concerned with what 
julia-cstparser is in this case.

Emacs should just magically load whatever it needs for the Julia REPL to 
work (whether
that's written in Julia or Python or whatever is an implementation 
detail--you COULD
have a Julia parser written in Python. Notably, most parsers for any 
language in
IntelliJ IDEA are written in Java--the Python parser, Rust parser etc).

That said, I'm totally open to other ways to do it.

The obvious alternative would be for the user to put julia-cstparser and 
julia-tokenize
into every Julia project's manifest.scm . But the error message is 
inscrutable if you
don't have those in there[1]--and I have no idea how any normal person 
would figure out
that julia-cstparser is needed in the first place.

[1] julia-snail--send-to-server: No Julia REPL buffer *julia* found; run 
julia-snail
Starting Julia process and loading Snail...
julia-snail--repl-enable: The REPL terminal buffer is inactive; 
double-check julia-snail-executable path

(In buffer "*scratch*" : )
julia-snail-executable
"julia"

(note: that "julia" excutable IS available in the manifest of the buffer 
env--and launching "julia" does work when launched manually within 
emacs)