# Dune preview install new package

**URL:** <https://discuss.ocaml.org/t/dune-preview-install-new-package/15472>\
**Category:** Ecosystem\
**Tags:** dune\
**Created:** [October 19, 2024, 1:28pm UTC](https://discuss.ocaml.org/t/dune-preview-install-new-package/15472 "2024-10-19T13:28:37Z")\
**Posts on this page:** 1\
**Showing post:** 2

<div class="post-metadata">

**Author:** ![v-gb](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/v-gb/32/5080_2.png) [@v-gb](https://discuss.ocaml.org/u/v-gb)\
**Post date:** [October 19, 2024, 2:44pm UTC](https://discuss.ocaml.org/t/dune-preview-install-new-package/15472/2 "2024-10-19T14:44:24Z")

</div>

Hi,

> [@nojaf](#):
>
> I created a project using `dune init project my_name`.  
> And now I’d like to play around with `ppx_deriving`.  
> Their GitHub says `opam install ppx_deriving`, so I thought `dune install ppx_deriving` would do the trick but nothing happens:
> 
> `Error: Unknown package ppx_deriving!`

There is no explicit install step. You’d want to add ppx\_deriving to your dune-project file, then call `dune pkg lock` (which dune tells you to do IIRC), and the next build will download/build any new dependencies. Doc: [Managing Dependencies - Dune documentation](https://dune.readthedocs.io/en/latest/tutorials/dune-package-management/dependencies.html).

`dune install` is not comparable to `opam install`, I guess its functionality and name is taken from the `make install` convention.

> [@nojaf](#):
>
> This is all rather strict, can I treat this warning as a warning?

You can add `[@@@ocaml.warnerror "-34-69"]` at the top of your file. The problem with warnings-as-not-errors is that warnings will only be given when the file is compiled. So if you run `dune build && dune build`, the second build will never report any warning.

> [@nojaf](#):
>
> Lastly, what do I tell the ocaml vscode extension:
> 
> ```auto
> The current Merlin configuration has been generated by another, incompatible, version of Dune. Please rebuild the project. (Using the same version of Dune as the one running the 'ocaml-merlin' server.)ocamllsp
> 
> ```
> 
> Does anyone have any pointers?

The tutorial should explain how to setup dev tools, but since it doesn’t, I think [this post](https://discuss.ocaml.org/t/ann-dune-developer-preview-updates/15160/7#p-65585-changes-since-last-update-2) is the only written explanation.

---

_[View the full topic](https://discuss.ocaml.org/t/dune-preview-install-new-package/15472)._