Add LSP to the Binder image

[krassowski]

Closes #24.

Binder: https://mybinder.org/v2/gh/krassowski/jupyterlab-plugin-playground/add-lsp?urlpath=lab

Note: we can hold this while I investigate migrating to a newer server (jupyter-lsp/jupyterlab-lsp#697) and we could improve the default theme of the completer so that the detail is shown below the label not next to it (so it is not as spread out).

[jtpio]

Thanks!

This is really great and incrementally lowers the bar for authoring small extensions.

I wonder if we can get autocomplete to work on the JupyterLab API as well, for example when trying complete methods on the palette:

[krassowski]

In TypeScript - yes (already works if types are provided); in JS - I don't think it is possible with either javascript-typescript-langserver nor typescript-language-server. Begs a question if we should consider using typescript with lax rules (allow implicit any, etc) and compile with tsc or babel instead.

[krassowski]

Instead of babel we could try sucrase as in ipython/ipython#13376 - definitely worth experimenting.

[bollwyvl]

compile with tsc ... sucrase

Hmm... I think figuring out a way to use the in-browser equivalent of tsc in the browser is going to give a developer better bang for their buck than babel or sucrase. While it is a bit heavy, it's the devil we know, and is going to have the best tooling.

On the broader point: the distribution of typings (or LSIF) should probably become a thing we by enable by default in e.g. @jupyterlab/builder and/or extension-cookiecutter-ts, depending on the work required.

Specifically on sucrase: while it seems to do a lot of nice things for interactive work, much like babel, some of the tricks it enables might not transfer well into a "production" extension.

[krassowski]

This now works (as in "the state is acceptable") but because the TypeScript filter expects the client to filter completions on their side we need to implement this to make it actually more useful; I opened jupyter-lsp/jupyterlab-lsp#728.

[krassowski]

Ok, going for tsc is actually feasible. We can use transformers to swap the imports with whatever we like (tokens for @jupyterlab/ and requires for anything else. Webpacking is an issue but there are know workarounds: microsoft/TypeScript#39436

[jtpio]

Looks good on Binder, thanks!