Re: [Caml-list] Setting up OPAM in emacs

[Francois Berenger <berenger@riken.jp>]

On 06/20/2013 01:06 AM, Ivan Gotovchits wrote:
> I don't (want to) understand the details of why opam switches don't
> work well with Emacs right now,

My guess is that it is because OPAM sets up env. variables
and emacs keep using the ones it knew once it was launched.

 > or of any of the proposed solutions.
> Is there a solution integrated in OPAM by now? If not, is there a
> consensus on what simple users like me should use to solve the
> problem? Could you (the thread participants) decide on something, and
> send that to the OPAM upstream, so that future versions solve this
> issue?
>
> (The immediate problem I observe is that compile-command does not use
> the OCaml versions I would expect it to, in general defaulting to my
> system OCaml -- that may depend on the way Emacs is launched. More
> sophisticated things such as being able to call "opam switch" from
> inside Emacs are probably secondary needs, and I would be fine with a
> basic integration not supporting that, and letting people hone their
> emacs-lisp skills for that.)
>
> On Tue, Jun 4, 2013 at 4:55 PM, Leo White <lpw25@cam.ac.uk> wrote:
>> My personal solution for Tuareg mode is to put:
>>
>>   ;; Use OPAM's ocaml
>>   (setq tuareg-interactive-program "opam config exec ocaml")
>>
>> in my .emacs.
>>
>> Regards,
>>
>> Leo
>>
>> Wojciech Meyer <wojciech.meyer@gmail.com> writes:
>>
>>> Christophe's function hook is probably much better and elegant solution,
>>> but this works for me:
>>>
>>>>>
>>> (defun dm-opam-switch-root (ocaml-version opam-root)
>>>   (interactive "sOCaml version: \nsOPAM root: ")
>>>   (let* ((path (if (string-match "\\.opam" (car exec-path)) (cdr exec-path) exec-path))
>>>          (entry
>>>           (replace-regexp-in-string
>>>            "\n" ""
>>>            (shell-command-to-string
>>>             (format "opam switch --root %s %s > /dev/null && opam config env | sed -n 's/^PATH=\\([^:]\\+\\):.*$/\\1/p'" opam-root ocaml-version))))
>>>          (env-path (replace-regexp-in-string "\n" "" (shell-command-to-string (format "opam config env --root %s | sed -n 's/^PATH=\\(.*\\)/\\1/p'" opam-root)))))
>>>     (setq exec-path (cons entry path))
>>>     (setenv "PATH" env-path)))
>>>
>>> (defun dm-opam-switch (ocaml-version)
>>>   (interactive "sOCaml version: ")
>>>   (dm-opam-switch-root ocaml-version "~/.opam"))
>>> <<
>>>
>>> I wouldn't say myself it's a perfect script, but it works. Note that I
>>> use a lot of shell trickery instead of Emacs buffers, which is probably
>>> not a good idea.
>>>
>>> You just say M-x dm-opam-switch, and indicate which version you would
>>> like.
>>>
>>> Best,
>>> Wojciech
>>>
>>> Christophe TROESTLER <Christophe.Troestler@umons.ac.be> writes:
>>>
>>>> On Tue, 28 May 2013 09:59:53 +0400, Ivan Gotovchits wrote:
>>>>>
>>>>> 2. Use «eval `opam env config`» in the begining of a compile-command.
>>>>>    This works fine when you switch compiler, but other commands, such as
>>>>>    «C-c C-s» doesn't use new environment.
>>>>
>>>> I use this for the compilation:
>>>>
>>>>     ;; OPAM compilation — one must update to the current compiler
>>>>     ;; before launching the compilation.
>>>>     (defadvice compile (before compile-opam activate)
>>>>       "Run opam to update environment variables"
>>>>       (set (make-local-variable 'compilation-environment)
>>>>         (with-temp-buffer
>>>>           (ignore-errors (call-process "opam" nil t nil "config" "-env"))
>>>>           (goto-char (point-min))
>>>>           (while (re-search-forward "; *export.*$" nil t)
>>>>             (replace-match "" nil nil))
>>>>           (split-string (buffer-substring 1 (point-max)))
>>>>           )))
>>>>
>>>> For the toplevel, I am afraid one needs to restart it.  I guess a
>>>> similar trick is possible to automatically select the right one.
>>>>
>>>> Hope it helps,
>>>> C.
>>
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>