# Install Ocsigen

**URL:** <https://discuss.ocaml.org/t/install-ocsigen/755>\
**Category:** Ecosystem\
**Tags:** lwt, opam, ocsigen\
**Created:** [August 23, 2017, 8:31am UTC](https://discuss.ocaml.org/t/install-ocsigen/755 "2017-08-23T08:31:13Z")\
**Posts on this page:** 20\
**Page:** 1

<div class="post-metadata">

**Author:** ![mico](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/mico/32/401_2.png) [@mico](https://discuss.ocaml.org/u/mico)\
**Post date:** [August 23, 2017, 8:31am UTC](https://discuss.ocaml.org/t/install-ocsigen/755/1 "2017-08-23T08:31:13Z")

</div>

Hi,

I do opam install eliom (after opam upgrade) and I receive :  
The following dependencies couldn’t be met:

- ocsigenserver -\> lwt \< 3.0.0  
Your request can’t be satisfied:
- No package matches lwt\<3.0.0.

No solution found, exiting

And opam show lwt says :  
package: lwt  
version: 3.1.0  
I started with Ocaml and Opam yesterday, I prefer to ask advice.

Thanks

---

<div class="post-metadata">

**Author:** ![dbuenzli](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/dbuenzli/32/18_2.png) [@dbuenzli](https://discuss.ocaml.org/u/dbuenzli)\
**Post date:** [August 23, 2017, 8:48am UTC](https://discuss.ocaml.org/t/install-ocsigen/755/2 "2017-08-23T08:48:26Z")

</div>

IIRC this looks like an error message from the broken internal solver. Could you please report the output of `opam config report`.

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<div class="post-metadata">

**Author:** ![mico](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/mico/32/401_2.png) [@mico](https://discuss.ocaml.org/u/mico)\
**Post date:** [August 23, 2017, 8:51am UTC](https://discuss.ocaml.org/t/install-ocsigen/755/3 "2017-08-23T08:51:56Z")

</div>

Thanks for your attention.

```auto
# OPAM config report
# opam-version 1.2.2 
# self-upgrade no
# os linux
# external-solver no
# criteria -removed,-notuptodate,-changed
# jobs 4
# repositories 3* (http)
# pinned 0
# current-switch system*
# last-update 2017-08-22 20:46

```

---

<div class="post-metadata">

**Author:** ![dbuenzli](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/dbuenzli/32/18_2.png) [@dbuenzli](https://discuss.ocaml.org/u/dbuenzli)\
**Post date:** [August 23, 2017, 8:56am UTC](https://discuss.ocaml.org/t/install-ocsigen/755/4 "2017-08-23T08:56:49Z")

</div>

> [@mico](#):
>
> external-solver no

opam is no longer able to function correctly on the current opam OCaml respository with the internal solver (it will be [removed](https://github.com/ocaml/opam/issues/2989) in the next version of opam). You will have to install an external solver, see [here](http://opam.ocaml.org/doc/Install.html#ExternalSolvers).

---

<div class="post-metadata">

**Author:** ![mico](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/mico/32/401_2.png) [@mico](https://discuss.ocaml.org/u/mico)\
**Post date:** [August 23, 2017, 9:01am UTC](https://discuss.ocaml.org/t/install-ocsigen/755/5 "2017-08-23T09:01:02Z")

</div>

Thanks !

I have done sudo apt install aspcud

Could you give me the command line ?

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<div class="post-metadata">

**Author:** ![mico](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/mico/32/401_2.png) [@mico](https://discuss.ocaml.org/u/mico)\
**Post date:** [August 23, 2017, 9:04am UTC](https://discuss.ocaml.org/t/install-ocsigen/755/6 "2017-08-23T09:04:17Z")

</div>

i try with  
opam install eliom --solver=aspcud

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<div class="post-metadata">

**Author:** ![dbuenzli](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/dbuenzli/32/18_2.png) [@dbuenzli](https://discuss.ocaml.org/u/dbuenzli)\
**Post date:** [August 23, 2017, 9:14am UTC](https://discuss.ocaml.org/t/install-ocsigen/755/7 "2017-08-23T09:14:18Z")

</div>

AFAIK you should not have to do anything. Just check that `opam config report` reports an external solver.

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<div class="post-metadata">

**Author:** ![mico](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/mico/32/401_2.png) [@mico](https://discuss.ocaml.org/u/mico)\
**Post date:** [August 23, 2017, 9:19am UTC](https://discuss.ocaml.org/t/install-ocsigen/755/8 "2017-08-23T09:19:47Z")

</div>

Just

```auto
 dbm.1.0 troobleshooting =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
=> This package relies on external (system) dependencies that may be missing. `opam depext dbm.1.0' may help you find the correct installation for your system.

```

and opam config report :

```auto
# OPAM config report
# opam-version 1.2.2 
# self-upgrade no
# os linux
# external-solver aspcud $in $out $criteria
# criteria -count(removed),-notuptodate(request),-sum(request,version-lag),-count(down),-notuptodate(changed),-count(changed),-notuptodate(solution),-sum(solution,version-lag)
# jobs 4
# repositories 3* (http)
# pinned 0
# current-switch system*
# last-update 2017-08-22 20:46

```

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<div class="post-metadata">

**Author:** ![anon72795300](https://avatars.discourse-cdn.com/v4/letter/a/8e7dd6/32.png) [@anon72795300](https://discuss.ocaml.org/u/anon72795300)\
**Post date:** [August 23, 2017, 9:22am UTC](https://discuss.ocaml.org/t/install-ocsigen/755/9 "2017-08-23T09:22:23Z")

</div>

@mico, I think you should use triple backticks for pasting reports and code:

````
```
code or report
```

````

That will preserve formatting.

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<div class="post-metadata">

**Author:** ![dbuenzli](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/dbuenzli/32/18_2.png) [@dbuenzli](https://discuss.ocaml.org/u/dbuenzli)\
**Post date:** [August 23, 2017, 9:24am UTC](https://discuss.ocaml.org/t/install-ocsigen/755/10 "2017-08-23T09:24:56Z")

</div>

> [@mico](#):
>
> external-solver aspcud $in $out $criteria

Good so there’s no need for you to specify the --solver=aspcud I hope you managed to get some things installed…

> [@mico](#):
>
> dbm.1.0 troobleshooting =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
> 
> =\> This package relies on external (system) dependencies that may be missing. `opam depext dbm.1.0’ may help you find the correct installation for your system.

Try

```auto
opam install depext 
opam depext dbm

```

which will help to install the needed dependencies on your system.

---

<div class="post-metadata">

**Author:** ![mico](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/mico/32/401_2.png) [@mico](https://discuss.ocaml.org/u/mico)\
**Post date:** [August 23, 2017, 9:32am UTC](https://discuss.ocaml.org/t/install-ocsigen/755/11 "2017-08-23T09:32:28Z")

</div>

I works fine. Thank you very much for your attenion

An other problem 🙂  
opam install ocsigen-start  
[ERROR] ocsigen-start is not available because your system doesn’t comply with ocaml-version \>= “4.03”.

I have indeed OCaml version 4.02.3  
I installed ocmal with apt-get and then coq and then coqide (hard work).

If i remove ocaml with apt-get purge before to install the latests version of caml, there is a risk for coq and coqide ?

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<div class="post-metadata">

**Author:** ![dbuenzli](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/dbuenzli/32/18_2.png) [@dbuenzli](https://discuss.ocaml.org/u/dbuenzli)\
**Post date:** [August 23, 2017, 9:35am UTC](https://discuss.ocaml.org/t/install-ocsigen/755/12 "2017-08-23T09:35:44Z")

</div>

You can just leave your system install of ocaml in peace and use another [switch](https://opam.ocaml.org/doc/Usage.html#opamswitch) for ocsigen do

```auto
opam switch 4.03.0
eval $(opam config env)
opam install ocsigen-start

```

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<div class="post-metadata">

**Author:** ![mico](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/mico/32/401_2.png) [@mico](https://discuss.ocaml.org/u/mico)\
**Post date:** [August 23, 2017, 9:54am UTC](https://discuss.ocaml.org/t/install-ocsigen/755/13 "2017-08-23T09:54:38Z")

</div>

done thanks

it is like virtualenv in Python ?

---

<div class="post-metadata">

**Author:** ![mico](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/mico/32/401_2.png) [@mico](https://discuss.ocaml.org/u/mico)\
**Post date:** [August 23, 2017, 9:57am UTC](https://discuss.ocaml.org/t/install-ocsigen/755/14 "2017-08-23T09:57:59Z")

</div>

Thank you 🙂

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<div class="post-metadata">

**Author:** ![mico](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/mico/32/401_2.png) [@mico](https://discuss.ocaml.org/u/mico)\
**Post date:** [August 23, 2017, 10:05am UTC](https://discuss.ocaml.org/t/install-ocsigen/755/15 "2017-08-23T10:05:37Z")

</div>

the last step 😉

```auto
mchl@shemesh:~/ocaml/ocsigen$ eliom-distillery -name myapp -template os.pgocaml
The program 'eliom-distillery' is currently not installed. You can install it by typing:
sudo apt install eliom
mchl@shemesh:~/ocaml/ocsigen$ opam install eliom
[NOTE] Package eliom is already installed (current version is 6.2.0)
```

---

<div class="post-metadata">

**Author:** ![dbuenzli](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/dbuenzli/32/18_2.png) [@dbuenzli](https://discuss.ocaml.org/u/dbuenzli)\
**Post date:** [August 23, 2017, 11:53am UTC](https://discuss.ocaml.org/t/install-ocsigen/755/16 "2017-08-23T11:53:05Z")

</div>

Maybe a missing `eval $(opam config env)` in your shell.

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<div class="post-metadata">

**Author:** ![mico](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/mico/32/401_2.png) [@mico](https://discuss.ocaml.org/u/mico)\
**Post date:** [August 23, 2017, 12:16pm UTC](https://discuss.ocaml.org/t/install-ocsigen/755/17 "2017-08-23T12:16:11Z")

</div>

not at all : i followed the instructions

---

<div class="post-metadata">

**Author:** ![dbuenzli](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/dbuenzli/32/18_2.png) [@dbuenzli](https://discuss.ocaml.org/u/dbuenzli)\
**Post date:** [August 23, 2017, 12:17pm UTC](https://discuss.ocaml.org/t/install-ocsigen/755/18 "2017-08-23T12:17:45Z")

</div>

Sorry I can’t help further then as I don’t know about `eliom` maybe the `eliom-distillery` tool is distributed by another package.

---

<div class="post-metadata">

**Author:** ![mico](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/mico/32/401_2.png) [@mico](https://discuss.ocaml.org/u/mico)\
**Post date:** [August 23, 2017, 12:38pm UTC](https://discuss.ocaml.org/t/install-ocsigen/755/19 "2017-08-23T12:38:48Z")

</div>

☀ thank you very much and have an nice day 🙂

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<div class="post-metadata">

**Author:** ![yawaramin](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/yawaramin/32/3384_2.png) [@yawaramin](https://discuss.ocaml.org/u/yawaramin)\
**Post date:** [August 23, 2017, 2:04pm UTC](https://discuss.ocaml.org/t/install-ocsigen/755/20 "2017-08-23T14:04:49Z")

</div>

> [@mico](#):
>
> it is like virtualenv in Python ?

A bit more powerful:

- You can have a specific OCaml compiler version as well as associated libraries for each of your projects
- You can alias a switch (give it a specific name) so that it’s easy to remember
- Upcoming opam version will allow you to automatically install the specific compiler and library versions for a project when you download the project and start working on it.

[Next page](https://discuss.ocaml.org/t/install-ocsigen/755.md?page=2)