How to implement LSP for a multi-language kernel (SoS)?

Many thanks for your great work on language server support. I have just tried jupyterlab-lsp, which works great for Python and R, but unfortunately does not work for a multi-language kernel SoS that I have developed.

The idea behind of SoS is that it is a superkernel that sits between frontend and other kernels (see this illustration for details). It allows the use of multiple kernels in one notebook (through sos-notebook for classic jupyter and jupyterlab-sos for jupyterlab), and allows data exchange among live kernels.

The reason why jupyterlab-lsp does not work with SoS is simple: it does not know what language SoS is. If we are to solve this problem, there needs to be some way for SoS to notify jupyterlab-lsp the language used for each cell. I can work at both the frontend and backend (e.g. write a language server for SoS), but I am not sure if cell-level language support is at all possible with jupyterlab-lsp. I would appreciate any insight from the developers if and how this can be done. Thanks.

[BoPeng]

Okay, instead of creating sos-language-server, why don’t we just use per-cell language-server as we already do with cell magics for IPython? This should be simple to implement.

That will make things much easier for SoS. SoS currently uses kernel meta data to specify the kernel of each cell, but I am willing to change that to whatever will be used by jupyterlab-lsp.

BTW, congratulations on the merge of https://github.com/jupyter/enhancement-proposals/pull/72 !

[BoPeng]

Yes, this is on my TODO list, even relatively high, but I am swamped with other obligations (covid related projects, not surprisingly) and have not been able to work on this.