Language Servers and Emacs

[Perry E. Metzger]

Microsoft has invented an interesting new protocol for IDEs
and code editors to talk to language tools (like compilers) to do
things like smart autocompletion, jumping to code definitions, and the
like.

The idea is that compilers and similar tools generally know a lot
about the structure of a language and can provide help to an editor as
an external service, so the editor doesn't need to handle parsing,
symbol tables, etc. for the language on its own. The editor can just
ask the compiler or language tool for the information when it needs
it.

The protocol is open and they have no intellectual property claims on
it. It is JSON based and should be straightforward to support.

A general description is at:

http://langserver.org/

And detailed protocol information is at:

https://github.com/Microsoft/language-server-protocol

It was originally designed for their "Roslyn" C# compiler (which is
free software, it's Apache licensed) to integrate with their own
editors and IDEs, but other compiler projects and editors seem to be
adopting the thing. There are now language servers people have built
for a lot of languages, and there's support appearing for the
protocol in a bunch of editors.

I'm mentioning this here because I think the Emacs community would be
interested in this capability, though I suspect that it would also be
really neat if GCC developed a language server for C and C++.

I recall that a while ago, RMS had a lot of problems with the idea
of opening up GCC in ways that might have made it possible for people
to use it too much for proprietary compilers. Using the Language
Server Protocol, it should be possible for GCC and other free
language tools to talk to a variety of IDEs and Editors (including, I
hope, Emacs) to allow advanced modern code editing _without_ the
sorts of risks he was worried about.

Perry
-- 
Perry E. Metzger                address@hidden