eml editor support

[aantron]

Would solve the underlying issues of #55, but might be major work. cc @tmattio

[tmattio]

This can go to https://github.com/ocamllabs/vscode-ocaml-platform/ if you want. I'm planning on spending some time on this, starting with syntax highlighting that supports both OCaml and HTML.

[tmattio]

Just posted an update here: #156 (comment)

Hi!

I'm maintaining the OCaml VSCode extension and contributing to the LSP server, so I wanted to give some > perspective on supporting .eml files from there.

While we can certainly add syntax support in the extension for .eml files (to have the syntax highlighting for > both OCaml and HTML, not one or the other as is currently the case with the extension workaround), having full > support for .eml file, with error reporting, is unlikely to happen as it would require support for the syntax > all the way down to Merlin.
The good news is, once Dune 3.0 is release, it will be integrated in the LSP server, so Dune errors (as opposed to > Merlin errors) will be reported in the source code as well. Unfortunately, it won't be as exhaustive as Merlin: > only the first error of the file will be reported, as Dune (and the compiler) are only able to give the first > error.

I believe the experience once the syntax is supported and Dune 3.0 is integrated in the LSP will be acceptable. > But of course, it will be missing important features such as code completion, code actions, etc.

If we want to have these features, we have two options:

• Using PPX for .eml files instead of a custom file generator.
• Adding support for eml syntax in Merlin.

Note that we are currently going through the application period for the Winter Outreachy session. One of the > project is to add support for .eml in the extension (along with other syntaxes if time allows). So if we find an > intern, this should come soon.

[aantron]

I want to link to a WIP PR on syntax highlighting support here ocamllabs/vscode-ocaml-platform#895.