Re: [Caml-list] Errors in installing 'lwt'

[Helmut Brandl <helmut.brandl@gmx.net>]

Thanks for the hint Francois. The command sequence you proposed worked 
successfully.

However can you explain to me what I have now. I think I have now two 
versions of the ocaml compiler installed, one system wide (4.02.0) and 
one installed by opam (4.01.0).

If I use a fresh shell I still get version 4.02 until I issue the 'eval' 
command to get the new paths. If I try to switch back to 4.02 opam tries 
to install 4.02 from scratch, i.e. it does not use the system installation.

Is there any possibility to switch back to the system installation in 
the same shell or do I need to use a fresh shell?

I still feel uncomfortable because I don't know why the installation of 
'lwt' fails with my system installation of ocaml.

Regards
Helmut


On 10/20/2014 10:25 AM, Francois Berenger wrote:
> On 10/20/2014 05:19 PM, Helmut Brandl wrote:
>> How do I install ocaml by opam? The command 'opam install ocaml' does
>> not work.
>
> opam switch 4.01.0 # just an example version
> eval `opam config env` # use it
> opam install lwt # your initial goal
>
>> What is the difference? My ocaml system works fine and I don't want to
>> compromise it because I need it.
>
> It won't be compromised in any way, opam will just ignore it.
>
>> Can 2 versions of ocaml coexist without any interference?
>
> That's one of the many goals of OPAM, I believe.
> OPAM's switch command allows you to "jump" between ocaml versions.
>
>> On 10/20/2014 10:08 AM, Francois Berenger wrote:
>>> As a workaround, I would recommend having a fresh ocaml installed by
>>> opam.
>>>
>>> It always work nicer in this way, in my experience (I use the ocaml
>>> installed by opam switching, not the one installed system-wide).
>>>
>>> On 10/20/2014 04:56 PM, Helmut Brandl wrote:
>>>> My platform is the 32bit version of the archlinux distribution on 
>>>> x86. I
>>>> have got the ocaml base installation and opam via the distribution and
>>>> tried to install packages via 'opam install ...'.
>>>>
>>>> Everything went fine until 'opam' tried to install 'lwt'.
>>>>
>>>>
>>>>
>>>> On 10/20/2014 09:50 AM, John Whitington wrote:
>>>>> Hi,
>>>>>
>>>>> Helmut Brandl wrote:
>>>>>> Does not work either. 'opam' reinstalls 'camlp4' without any 
>>>>>> problems
>>>>>> but then fails installing 'lwt'.
>>>>>
>>>>> You haven't mentioned what platform you're using. There's a known
>>>>> issue on OS X with 2.4.6, for example:
>>>>>
>>>>> https://github.com/ocsigen/lwt/issues/91
>>>>>
>>>>> Thanks,
>>>>>
>>>>
>>>
>>
>>
>