Allow using LSP in the Monaco Editor

[alexdima]

We should make it easy for a Monaco Editor user to easily plug in a rich language via LSP.

We should investigate if existing solutions, like https://github.com/TypeFox/monaco-languageclient , work well enough.

[kaisalmen]

Hi @hediet I was just made aware of this issue by @CGNonofr . We both maintain https://github.com/TypeFox/monaco-languageclient and @CGNonofr created https://github.com/CodinGame/monaco-vscode-api which supplies a modularized VS Code Web.

Very recently I wrote a blog post about monaco-languageclient v10 which contains a good summary of the project's history.

Please reach out to us if you have any questions? We are open to collaborate on the subject.

[hediet]

Thanks for reaching out, @kaisalmen! We greatly appreciate your work on making the monaco editor more useful!

It seems like the monaco-languageclient and monaco editor LSP feature as described by this issue serve different purposes.
The main motivation of adding first class/built-in LSP support to the monaco editor is to prepare the monaco editor to be used by the typescript playground with the upcoming LSP-based tsgo language server.
Besides that, it would also allow us to do some code cleanup with the existing css/json/html/typescript that uses a custom protocol to forward language requests to the web worker. These are mostly single-file use-cases for when someone needs a lightweight embedded editor, not with the intention to become a full-fledged IDE.

If I understand correctly, the heavy lifting of monaco-languageclient is done by mapping the vscode API to the monaco editor API. Then, the official vscode LSP client can be used to connect an LSP server to the vscode API, and thus making it available to the monaco editor. This would also make it very easy to make VS Code extensions available to the monaco-editor.
However, the complexity of this approach is significantly higher and the control over the LSP part much lower, as it uses the vscode-languageclient package that is just intended to be used as part of VS Code extensions.

For our use-case, it seems more suited to map LSP directly to monaco-editor API, instead of using vscode-languageclient to map it to VS Code API and then mapping the VS Code API to monaco editor API.
(though I'm aware that VS Code itself maps the VS Code API to the monaco editor API)

Hope that makes sense - let me know if you have any concerns!