Langium Weekly Dev-Meeting

[msujew]

Hi everyone!

Developers and everyone interested meet every Wednesday at 4PM CET, to discuss anything related to the development of Langium. If you want to bring up a specific topic at the next meeting, please add it as a comment/edit to the agenda below. We will keep short notes on each topic. Sort the comments below by Newest to stay up to date on the latest dev-meeting notes.

Google Meet

The dev-meeting will be held using google meet:

https://meet.google.com/bcm-iqtq-egm

Community Calendar

An open calendar is available to include the dev meeting and other relevant events in your personal or business calendar:

https://calendar.google.com/calendar/u/0?cid=Y19rbGJlbnJnbW5vMWkwbG1uM3FzdDAwZzI3Z0Bncm91cC5jYWxlbmRhci5nb29nbGUuY29t

[msujew]

Agenda 29/06/2022

• [@msujew] Discuss roadmap (See result here Roadmap Q3 2022 #573)
• [@spoenemann] Website showcase is ready to review now: Statemachine browser showcase langium-website#52
• [@gfontorbe] Refactoring the References service to be used by all relevant LSP services
• [@montymxb] Discussion on whether inferred types are allowed to extend declared types

[msujew]

Agenda 06/07/2022

• [@spoenemann] Enable type resolution across files (Interface defines in a Langium file isn't accessible from another #507)
• [@msujew] Anyone interested in creating a PR for Native Monarch support for Langium #582?

[msujew]

Agenda 13/07/2022

• [@msujew] I've created a (incomplete) list of LSP interfaces that we should support: Support full LSP spec #595
• [@msujew] Anyone up for reviewing Support workspace/executeCommand LSP request #592?

[msujew]

Agenda 20/07/2022

• [@sailingKieler] Roadmap on type inference refactoring
• [@msujew] Continued work on web mode
• [@msujew] Currently looking into refactoring completion, I noticed major issues

[msujew]

Agenda 27/07/2022

[msujew]

Agenda 03/08/2022

• [@pluralia & @sailingKieler] Type inference of non-optional assignment actions
• [@pluralia] Ideas for refactoring the grammar language
• [@msujew] Working on guides for scoping (WIP)

[msujew]

Agenda 10/08/2022

• [@msujew] Completion refactoring has finally finished! Completion service refactoring #623
• [@msujew] Formatting tests Support formatting testing #626

[spoenemann]

Meeting on 17/08/2022 is canceled

None of the current maintainers of Langium are available next Wednesday, so we have to cancel that meeting.

[msujew]

Agenda 24/08/2022

[montymxb]

Agenda 31/08/2022

• [@sailingKieler & @spoenemann ] It would be nice to write up a guide to describe how to create built-in libraries in Langium, related issue
• [@montymxb] Monaco grammar file generation for Langium has been revised again, will give highlighting for Langium in the web.

[goto40]

If you are interested, I could try to provide some minimal examples... If yes: would I place the example or examples in the examples folder of langium or somewhere else? Should we specify the solution first (e.g. a variation of the hello world example with built in persons)?

[snarkipus]

For the uninitiated, what is the use case/utility of built-in libraries? I analyzed your codebase @goto40 but it wasn't immediately obvious to me since I'm unfamiliar with your DSL or its context.

[msujew]

@snarkipus The usual use case would be to declare built-in types that can be referenced by any user of the language without needing to declare them explicitly. One obvious example would be the built-in library of TypeScript, which contains all statically available classes/global variables of JavaScript. The process variable in Node.js for example is exposed that way. We never need to declare it, it's "just there".

[goto40]

As @msujew said: the use case is to provide built-in models, like types (in a language providing types, this could be a default library of default types, line uint32).

A simple example I could try to provide would be the Hello-World-Grammar with some predefined persons. So you could say "Hello MrPredefined1" with some predefined persons (like MrPredefined1). Different ways to provide this predefined models, as sketched by @spoenemann could be assembled in the provided example (or examples)...

[snarkipus]

Thanks @msujew & @goto40 for the explanation! If I've learned anything from this, it's definitely how much functionality modern languages have intelligently baked-in.

[msujew]

Agenda 07/06/2022

[@spoenemann] Performance with large workspaces: how to unload / on-demand-load workspace documents?

• Background: when resolving cross-references, we are already able to load the target document on demand (linker.ts). This capability is currently unused because we keep the whole workspace in memory after initial indexing. An alternative with potentially better performance in terms of initialization time and memory usage would be to only gather exported symbols into the index upon initialization of the language server instead of fully linking and validating all documents, and to unload (remove from memory) the documents and their ASTs afterwards. The big question is what happens when a user loads a document on demand when following a link. That document will be unprocessed, so it won't be possible to navigate references within it.

[msujew]

Agenda 14/09/2022

• [@spoenemann] Langium 0.5 milestone planning. Release is planned at the end of September.
• [@pluralia] Thoughts on Hacktoberfest?

[snarkipus]

@pluralia @msujew I'd be happy to register/participate (as long as the definition of 'pristine' is loose). If you didn't want to 'opt-in' or advertise that Langium is a Hacktoberfest participant, I think you would just need to tag the PRs as HACKTOBERFEST-ACCEPTED.

[pluralia]

@snarkipus, thank you for your attention! I and @montymxb (who initially proposed to participate in Hacktoberfest) discussed issues: there aren't suitable questions in the main repo right now, but adding details to the description of some of them might help. Also, there are suitable issues in other repos under langium organization. We discuss it in tomorrow's Langium Dev-Meeting.

[msujew]

Agenda 21/09/2022

• [@msujew] Release in one week, please review PRs as long as they're hot and fresh :)
• [@pluralia & @montymxb] Hacktoberfest issues

[snarkipus]

@montymxb @pluralia Just following up on Hacktoberfest. Unfortunately, work prevented me from being able to attend today.

[spoenemann]

Agenda 28/09/2022

• [@spoenemann] Release 0.5.0 will be published after the currently assigned PRs are merged.

[pluralia]

Agenda 05/10/2022

• Release 0.5.0 is published 🎉
• [@pluralia] Issues for langium-lox / "roadmap" to implement own DSL
• [@pluralia] Special syntax for infix operators

[snarkipus]

Congratulations on 0.5!

[goto40]

Same from me: congratulations. Thank you for this good work! I noticed that code completion (custom scope providers) works much better now!! In cases where I got many confusion propositions before I get the correct list now. I am very happy with that.

[msujew]

@goto40 Glad to hear that. The completion refactoring had a long time coming (see #623), but I'm also very happy with how the new version performs. There are still some tweaks we need to perform, but it works well for now.

[msujew]

Agenda 04/06/2025

• [@msujew] Light attendance, some discussion around v4.0 of Langium.

[msujew]

Agenda 11/06/2025

[msujew]

Agenda 18/06/2025

• [@msujew] The Support multi-target references #1509 PR is almost ready for another review (just need to finish a validation).
• [@msujew] The Support discarding the CST to preserve memory #1733 PR will not get into the v4.0 release and has been marked as a draft PR for now. We don't have a use case and don't want to increase the complexity of the framework too much.

[msujew]

Agenda 25/06/2025

[msujew]

Agenda 02/07/2025

• [@msujew] Released patch for [email protected], which fixes a bug in the EBNF generator.
• [@msujew] Discussed the 4.0 release:
  • Will create a preview release tomorrow
  • Will then go into a testing phase
  • Official release planned for the 23rd of July.

[msujew]

@cdietrich Preview release 3.5.0-next.936a9d7 is available now for testing :)

[msujew]

Agenda 09/07/2025

• [@msujew] Apparently Langium is now used (transitively) by more than 20,000 repos: https://github.com/eclipse-langium/langium/network/dependents
• Discussed Improve generated ast.ts regarding multiple languages #1979 (comment)

[msujew]

Agenda 16/07/2025

• [@msujew] TypeFox is unavailable due to a team retreat - will continue next week.

[msujew]

Agenda 23/07/2025

• [@msujew] Release is awaiting a few last PRs to land.

[msujew]

Agenda 30/07/2025

• [@msujew] Langium v4 release tomorrow. Any last changes that should get into that?

[msujew]

Agenda 06/08/2025

• [@msujew] Langium v4 release out now.

[msujew]

Agenda 13/08/2025

[msujew]

Agenda 20/08/2025

• [@msujew] No feedback from the 4.0 version, while we already have >6.000 weekly downloads on that version. Seems like everything runs smoothly :)

[msujew]

Agenda 27/08/2025

• [@msujew] I noticed a few issues with the infix operators (if they have 0 or 1 argument), I'll get to fixing those this & next week. Afterwards, we can create a PR to the documentation to properly document these features.

[msujew]

Agenda 03/09/2025

• [@msujew] Fixed a few issues wrt. infix operator rules. Will release a patch release ASAP.

[msujew]

Agenda 10/09/2025

• [@msujew] All fixes have been merged, I've created a patch release 4.0.1 today. Will do the PR for the changelog later.