Proposal: Include EBNF Grammars

[bemafred]

Proposal: Include EBNF Grammars with Language Feature Specifications

As the C# language evolves, feature specs have become an excellent way to communicate syntax, intent, and edge cases.

But for tool builders and formalists, we’d love to propose an additional artifact alongside feature specs:

✅ A formal, machine-readable EBNF grammar segment for each new syntax rule or update.

Why?

• Enhances clarity for both humans and parsers
• Enables downstream tooling to verify conformance or extend capabilities
• Supports educational tools and LLM-powered assistants that rely on grammar-based reasoning
• Aids in documenting breaking and non-breaking grammar changes across versions

This could begin as a Markdown-compatible .ebnf section in each spec—or reference a central grammar repo.

---

We’ve begun collecting and organizing grammars here:

🔗 github.com/canyala/grammar-meta-standard

And applying them in an AI assistant project here:

🔗 github.com/bemafred/sky-omega-public

We’d love to collaborate with the language design team to formalize a clean, maintainable approach to grammar versioning.

Is this something the team would consider integrating or supporting?

— Sky Omega / Grammar-Meta-Standard

[AartBluestoke]

There is an older repo where someone has antlr for c#6 at https://github.com/antlr/grammars-v4/tree/master/csharp
(antlr is also referenced from https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/language-specification/lexical-structure )
A version of antlr is embedded in the webpage at https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/language-specification/grammar
I don't think there is a single consolidated place to look for the source for this grammar, but a good start could be done from those pages.

[jnm2]

I think newer specs typically include such grammar, e.g. https://github.com/dotnet/csharplang/blob/main/proposals/csharp-13.0/partial-properties.md#grammar. Just to confirm, does that link show the type of thing you are asking for?

Older specs did not, but ECMA-TC49-TG2, the C# standard committee, is working on catching up: https://github.com/dotnet/csharpstandard/blob/draft-v8/admin/v8-feature-tracker.md

[CyrusNajmabadi]

I'm going to close this out. I think this would be great to have. It just aligns more with the goals and process of dotnet/csharpstandard vs dotnet/csharplang or dotnet/roslyn. I would transfer, but github isn't allowing me. Feel free to start up a new discussion there! :)

[jnm2]

Saw this coming. Csharpstandard asks: did you mean to open this on csharplang?

[CyrusNajmabadi]

i think csharpstandard would be better. :)

[bemafred]

Thanks, I’ll post in csharpstandard.16 juni 2025 kl. 01:28 skrev Cyrus Najmabadi ***@***.***>: I'm going to close this out. I think this would be great to have. It just aligns more with the goals and process of dotnet/csharpstandard vs dotnet/csharplang or dotnet/roslyn. I would transfer, but github isn't allowing me. Feel free to start up a new discussion there! :) —Reply to this email directly, view it on GitHub, or unsubscribe.You are receiving this because you authored the thread.Message ID: ***@***.***>