Curated Grammars for C# : An invitation

[bemafred]

🧬 Curated Grammars for C#: A Collaborative Invitation

Hi Roslyn team 👋

As C# continues to evolve, its power and flexibility inspire a whole ecosystem of tools, analyzers, generators, IDEs—and now, language-aware assistants. But one key piece of infrastructure is still missing in action:

A versioned, machine-readable .ebnf grammar for each iteration of the C# language.

While Roslyn’s syntax trees and syntax models are detailed and expressive, the lack of formal grammar definitions makes it harder than it should be to:

• Write formal parsers and tokenizers outside of Roslyn
• Teach and explain the language in structured ways
• Build code-aware language models or assistants
• Ensure fidelity in codegen, transpilers, and DSL embeddings

We believe it’s time to curate the language in a format that’s precise, versioned, and useful across tooling domains.

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

An open repository designed to house EBNF grammars for many languages—organized, versioned, and open to community curation. C# deserves a prominent home here.

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

The applied side: a reasoning-first assistant grounded in RDF, .NET, and semantic tooling. Built not just to generate code—but to understand it. For that, it needs the full formal grammar.

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🤝 We're reaching out to:

• @dotnet/roslyn
• @dotnet/roslyn-compiler
• @dotnet/roslyn-analyzers
• @dotnet/docs

To ask:
Would the Roslyn team be open to collaborating on this effort—either by:

• Publishing formal EBNF representations based on the syntax definitions in Roslyn
• Or supporting a community effort to extract and maintain such grammars?

We're more than happy to help extract, adapt, and publish these definitions, version by version. Even a canonical starting point for C# 13 would be an enormous step forward.

Let's make the structure of the language as clear and accessible as its features.

— Sky Omega & Grammar-Meta-Standard Team

[CyrusNajmabadi]

You can find the latest syntactic grammar here: https://github.com/dotnet/roslyn/blob/main/src/Compilers/CSharp/Portable/Generated/CSharp.Generated.g4. Note that in four places at the end it calls out to certain lexical constructs***. Those can be found in: https://github.com/dotnet/csharpstandard/blob/draft-v8/standard/lexical-structure.md

*** The call outs are due to the deeper complexity here that is hard to express in a context free grammar.

Someone could extract that out into it's own file if motivated. I would recommend moving this request over to dotnet/csharpstandard as they are more likely to have the motivation and time for this sort of effort versus dotnet/roslyn or dotnet/csharplang.