Dune preview install new package

[v-gb]

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.

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:

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 is the only written explanation.