Add minimal Scala support - tree-sitter, Metals #7933

mprihoda · 2024-02-16T23:54:10Z

Adds

Scala syntax highlighting using tree-sitter-scala
basic Metals LSP support, without automatic installation

Most of the tree-sitter queries have been picked up and repurposed from tree-sitter-scala and nvim-treesitter projects.

Release Notes:

Added basic Scala syntax highlighting and Metals LSP support - Scala extensions#136

filipwiech

Thank you for working on this, it's great to see support for Scala! 🙂 I have left a few suggestions for a more complete and rounded integration, but I don't know if those would be required immediately or could be worked on later as a followup. 👍

filipwiech · 2024-02-17T10:00:38Z

crates/zed/src/languages/scala.rs

+        false
+    }
+
+    async fn installation_test_binary(


Maybe we could execute metals -v to test if the binary is properly installed (can be found on path) and runs. It should return exit code 0 and print version to the standard output (which perhaps could be used in the future to compare the installed and requested releases?). 🙂

filipwiech · 2024-02-17T10:06:04Z

crates/zed/src/languages/scala.rs

+        "metals"
+    }
+
+    async fn fetch_latest_server_version(


Maybe we could fetch the latest version from the official source: https://scalameta.org/metals/latests.json. It's a JSON file that contains latest release and snapshot versions. It's automatically updated and used by the Metals webpage/documentation (https://scalameta.org/metals/docs/) and plugins (Neovim, VS Code). See an example in the nvim-metals: https://github.com/scalameta/nvim-metals/blob/main/lua/metals/install.lua#L138. 🙂

filipwiech · 2024-02-17T10:11:42Z

crates/zed/src/languages/scala.rs

+        Ok(Box::new(()))
+    }
+
+    async fn fetch_server_binary(


Perhaps we could do what all the other editor integrations are doing (Neovim, Helix, etc.) and require the Coursier to be installed first by the user (probably would be good to describe it in the language documentation under docs/src/languages). Then it could be used to download any desired Metals version (for example to some Zed cache directory, to not conflict with anything else). Here's a reference from nvim-metals, but it basically boils down to somethng like this:

cs bootstrap --java-opt -Xss4m --java-opt -Xms100m org.scalameta:metals_2.13:1.2.1+9-e65409f2-SNAPSHOT -r sonatype:snapshots -o ~/path/metals -f

🙂

you can copy my coursier based installation from my WIP branch https://github.com/bishabosha/zed/blob/feature-add-scala/crates/zed/src/languages/scala.rs

filipwiech · 2024-02-17T11:14:03Z

crates/zed/src/languages/scala/outline.scm

@@ -0,0 +1,27 @@
+(class_definition


The original PR by @hmemcpy (#6982) contained overrides.scm as well and the WIP branch from @bishabosha (https://github.com/bishabosha/zed/tree/feature-add-scala) had locals.scm. Would it make sense to integrate these too (sorry, I'm not really familiar with how Zed's treesitter configuration works)? 🙂

From https://github.com/mprihoda/zed/blob/aeb9e97138d332643d1d5b74584a222a709212a0/crates/language/src/language.rs#L761 it seems that locals.scm would not be used. Overrides should, but I'm not sure what to use it for, I have to figure it out yet.

The queries in current state seem to be working quite fine, though I'm sure there is a lot to be improved upon.

I initially followed the comment in the code about the steps regarding adding a new language support, it mentioned copying the SCM files from the language's tree-sitter repo. The Scala one had those, so I copied them as-is, but haven't checked if they were actually used by Zed.

mprihoda · 2024-02-18T07:06:16Z

Thank you for the review, all the comments make very much sense and I considered merging @bishabosha's changes, but if at all possible, I would prefer to merge this and follow up with improvements in next PRs, as it would delay the initial Scala support without much additional value.

I know the current state works, as I'm using it to write production Scala code daily, but I can't myself vouch for the rest and I would be hard pressed for time to test it. If we merge it, @bishabosha and @hmemcpy can the chime in to improve upon it and we can start to collaborate. There are more languages with this basic LSP support already in Zed, so it does not seem to be impossible.

Of course, if you deem it not fit for merge yet, I will try to update it as soon as possible.

bishabosha · 2024-02-18T09:25:23Z

I'm fine either way, and good to just get some initial support ASAP. Just without those changes it's on the user to update metals rather than automatically get the latest version.

Also users are expected to have Coursier on the path following the standard download instructions, but metals is something you have to manually download

hmemcpy · 2024-02-18T09:27:27Z

I don't have strong opinions here, but I really like @bishabosha'approach of automatically downloading metals from github. Seems consistent with several other LSP implementations in zed, and the API is built for that.

mprihoda · 2024-02-18T13:16:08Z

I agree, installation is definitely good to have and Zed has the necessary functions prepared. But I also assume that any user trying Scala with Zed right now will probably have already working Metals setup with another editor and I wanted to get this out as soon as possible.

I'm fine either way, just let me know. If the installation or query tuning is necessary before initial merge, I'll be able to get to it within a few days.

bishabosha

well I tested this locally and im having a good experience on a scala-cli project, BSP is being connected to (so go-to definition of external library dependencies is working).

up to the Zed people now

rikr2sanchez

LGTM

filipwiech

Another idea for the future, to improve the overall out-of-the-box experience: #8188 has introduced a "native" way for LSP integrations to discover (and use) an already present server binary in case user has one installed. 👍

filipwiech · 2024-02-23T15:41:36Z

@mprihoda Looks like there are merge conflicts after the project structure rework in #8270. 👍

mprihoda · 2024-02-24T09:27:10Z

@mprihoda Looks like there are merge conflicts after the project structure rework in #8270. 👍

Rebased and updated onto current main, seems to be working again.

mprihoda · 2024-02-24T09:31:12Z

Another idea for the future, to improve the overall out-of-the-box experience: #8188 has introduced a "native" way for LSP integrations to discover (and use) an already present server binary in case user has one installed. 👍

I'll investigate the changes. They work with the environment, which I'm interested in anyway because of direnv support (#4977) - it would be very useful to be able to run the LSP server with properly configured PATHs from the project dir.

bishabosha · 2024-02-28T14:12:38Z

probably blocked until #7096

filipwiech · 2024-03-05T18:06:38Z

I'm not sure if this is blocked on the ongoing extensions work:

Extensions are still in an early phase and it may take a while before the language integrations could be moved there.
LSP integrations for other languages seem to proceed without any issues, see for example the recent Java work in Add Java language support #8813 and the previous discussions in Add Java language support #7712.

@maxbrunsfeld Is there anything we can do to help push this through? Also, pinging @SomeoneToIgnore since he's been involved in reviewing the Java integration efforts, which should be fairly similar in nature to Scala (JVM family tree). 🙂

Adds - Scala syntax highlighting using `tree-sitter-scala` - basic Metals LSP support, without automatic installation Most of the tree-sitter queries have been picked up and repurposed from [tree-sitter-scala](https://github.com/tree-sitter/tree-sitter-scala) and [nvim-treesitter](https://github.com/nvim-treesitter/nvim-treesitter/tree/master/queries/scala) projects.

maxdeviant · 2024-03-21T22:04:05Z

We have an initial version of providing language servers via extensions that is ready for use, so I think that Scala support can move to an extension.

We have a couple extensions in the repo that can serve as a reference: https://github.com/zed-industries/zed/tree/eaa803298ee078c38af4e2ccf753ed98b43a9859/extensions

I'm also happy to answer any questions for someone who wants to work on a Scala extension.

hmemcpy · 2024-03-28T17:17:44Z

Update: the extension is now available in the preview version (0.129.1), should hopefully land in stable next week!
The extension lives under the scalameta org, please report any issues there: https://github.com/scalameta/metals-zed

Thanks again for everyone's contributions!

cla-bot bot added the cla-signed The user has signed the Contributor License Agreement label Feb 16, 2024

SomeoneToIgnore assigned SomeoneToIgnore and maxbrunsfeld and unassigned SomeoneToIgnore Feb 17, 2024

filipwiech reviewed Feb 17, 2024

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mprihoda force-pushed the wip/zed-scala branch from aeb9e97 to d5b9d63 Compare February 20, 2024 21:57

bishabosha approved these changes Feb 21, 2024

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rikr2sanchez approved these changes Feb 22, 2024

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filipwiech approved these changes Feb 23, 2024

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mprihoda force-pushed the wip/zed-scala branch from d5b9d63 to 985c48f Compare February 24, 2024 09:16

mprihoda force-pushed the wip/zed-scala branch from 985c48f to 6428c91 Compare March 8, 2024 12:20

mprihoda force-pushed the wip/zed-scala branch from 6428c91 to ce7f7dc Compare March 8, 2024 12:20

maxdeviant closed this Mar 21, 2024

hmemcpy mentioned this pull request Mar 27, 2024

Scala extension #9859

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dabrowski-adam mentioned this pull request Apr 15, 2024

Scala zed-industries/extensions#136

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Add minimal Scala support - tree-sitter, Metals #7933

Add minimal Scala support - tree-sitter, Metals #7933

mprihoda commented Feb 16, 2024

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Add minimal Scala support - tree-sitter, Metals #7933

Add minimal Scala support - tree-sitter, Metals #7933

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