Re: Erlang + Emacs profile

[Maxim Cournoyer]

Hello Zelphir,

Zelphir Kaltstahl <zelphirkaltstahl@posteo.de> writes:

> Hello Guix users!
>
> What is your way of setting up a profile for Erlang development?
>
> There are some things I would like to have, some of which I already
> managed to get:
>
>   * [X] Erlang installed through Guix package manager in a separate profile
>   * [X] `erl` REPL available in that separate profile
>   * [X] an Emacs Erlang mode (installed it through M-x list-pack RET and
>     searched for erlang there)
>   * [_] org-mode babel erlang for literate programming in org-mode,
>     using the Guix installed erlang executable – I found
>     https://github.com/xfwduke/ob-erlang, which also seems to work, but
>     I do not know how to point it to the Guix installed Erlang, so that
>     it can actually run code. Currently it complains about not finding
>     Erlang. Does anyone know how to point it to the Erlang executable? I
>     created this issue: https://github.com/xfwduke/ob-erlang/issues/1

It just looks up erl from your PATH, so the problem must be that you
started Emacs from your user profile, which doesn't know about the
separate Guix profile you created which contains Erlang.

You'd have to start Emacs from an shell where your separate profile was
sourced, or fiddle with M-x setenv to fix this.  emacs-guix also has
some guix-set-emacs-environment procedure that can be used to augment
Emacs environment variables given a profile, but it seems broken at the
moment.

I just tried the following approach, where everything is managed by Guix
in a separate profile:

--8<---------------cut here---------------start------------->8---
;; file: manifest.scm
(specifications->manifest
 '("erlang"
   "emacs"
   "emacs-org"
   "emacs-erlang"
   "emacs-ob-erlang")) ;; freshly packaged for you ;-)
--8<---------------cut here---------------end--------------->8---

Then spawn an environment with

guix environment -m manifest.scm

And then ran the following experiment:

--8<---------------cut here---------------start------------->8---
# file: test.org

Put this in your ~/.emacs or evaluate it ad-hoc before running the
rest.

#+begin_src elisp
  (require 'org-tempo)                  
  (require 'ob-erlang)
  (org-babel-do-load-languages
   'org-babel-load-languages
   '((erlang . t)))
#+end_src

Example taken from: https://github.com/xfwduke/ob-erlang
With your cursor on the code block, I ran M-x org-babel-execute-src-block
#+BEGIN_SRC erlang :module tryerlang
start() ->
        io:format("hello world").
#+END_SRC

And it produced:
#+RESULTS:
: hello world
--8<---------------cut here---------------end--------------->8---

Hope this helps!

Maxim