Integrate HIE into sourcegraph

[mpickering]

sourcegraph is powered by language servers. It would be good to add proper Haskell support by writing an extension.

This amounts to starting up HIE in a docker container and then communicating with HIE using websockets. In theory writing the extension is then very easy using the lsp-client library but whether that is finished is unclear to me.

Relevant issues:

https://github.com/sourcegraph/sourcegraph/issues/2359
https://github.com/sourcegraph/lsp-client
Python example: https://sourcegraph.com/extensions/sourcegraph/python
https://www.npmjs.com/package/@sourcegraph/lsp-client
https://about.sourcegraph.com/blog/improving-language-support-in-2019

[mpickering]

Indeed it looks like the lsp-client library is finished.

sourcegraph/sourcegraph-go#28
sourcegraph/sourcegraph-go#36
sourcegraph/sourcegraph-typescript#106

[alanz]

I am pretty sure hie is already in sourcegraph, see this older commit: https://github.com/sourcegraph/lsp-adapter/blob/dc2ede25752a7a3878a5f63e4718dda0e096b8ab/dockerfiles/haskell-ide-engine/Dockerfile

[mpickering]

The lap-adapter approach appears to be deprecated. https://about.sourcegraph.com/blog/improving-language-support-in-2019