New version of my language server

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Hey!

I’ve added a bunch of updates to the elm-language-server I’ve created, some cool gifs to show off the various features.

I created it with the goal of having something as fast and reliable as the Elm compiler to use in editors on a specific large codebase (~300klc + another ~300kloc of generated code), where existing solutions did not cut it.

Since last time I talked about it on elm-slack, support for document symbols, formatting (via elm-format) and the ability to rename some things, along with various fixes to existing systems, have been added.

If you want to try it out, I’ve got a binary for apple silicon in the release, since that’s what I use myself. There are instructions with the versions of Haskell tools that can be used and also instructions for building it with Nix.

For what’s next, I intend to look into improving caching and am considering hover type inference.

https://github.com/WhileTruu/elm-language-server
https://github.com/WhileTruu/elm-language-server/releases/tag/v1.0

Let me know what you think! :slight_smile:

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600kloc of Elm, this is pretty impressive. What king of product are you developing ? How many views, message types, do you have ?

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It’s an accounting kind of a product. We have about 250 pages (Model, init, Msg, update, view), a few kind of just wrap common components used between multiple pages.

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Hi,

A smart move I think to base it off the Elm compiler, as that already has so much of what a language server needs.

Which IR does your language server use, is it the Canonical IR ?

I know my way around the compiler code quite well from working on the Guida Elm port - which areas would I look in to see the bulk of the language server code you have added ? Just curious to take a look and see.

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It uses the source AST for all the features. I’ve done a proof-of-concept level type inference thing, that requires doing things with the canonical representation.

I also recently removed warnings (missing types, unused imports and such), which were based on canonical and optimized stuff. I think that functionality was copied from elm-dev, and too slow for the way the server currently works.

I’ve tried to keep changes to the actual compiler to a minimum, just exposing functions mostly. Almost everything is in just one file elm-language-server/terminal/src/LanguageServer.hs at language-server · WhileTruu/elm-language-server · GitHub, there’s also a small reporting file in a folder with the same name as that file.

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Has anyone tried to set this up with Zed? That’s been my editor for some years now and would love to try out this language server.

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I’m trying it out on my system. It has the same name as the regular elm-language-server, so I didn’t have to change anything in my editor (helix) to use it.

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I’ve added some updates and published a version with linux x86 and arm binaries as well, although I only tested the macos one.

  • diagnostics now run on a different thread and are debounced, so saving a bunch of files at the same time is more pleasant
  • support for references and go to definition for more things, which also adds rename support for more things

@wolfadex I got it working with Zed, I needed to add jsonrpc version to messages and the config below:

"lsp": {
    "elm-language-server": {
      "binary": {
        "path": "absolute path to binary",
        "arguments": [],
      },
    },
  },

Zed was really slow to show references for me, it got them in under a second from the server and then took like 30 to display them. Not sure what that is about.
I haven’t created a release / binaries for the jsonrpc version commit yet.

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