Witness yaml

[coremoon]

Add YAML support for witness and arguments files

This PR solves issue #177 - "Witness files should not require explicit type annotations"

This PR is a refactoring on PR #190 - #190 can be skipped.

Summary

Add optional YAML format support for witness and arguments files with intelligent format detection. JSON remains the standard format; YAML is supported as an alternative when users prefer comments and documentation.

Changes

Core Implementation

• src/serde.rs: Add YAML parsing functions
  • from_file_with_types(): Intelligent format detection (JSON first, YAML fallback)
  • from_yaml_with_types(): Explicit YAML parser with witness: and arguments: sections
  • Support for both JSON formats (old nested + new flat) for backward compatibility

Format Support

JSON (Standard)

{
  "x": { "value": "0x0001", "type": "u32" },
  "y": { "value": "1000", "type": "u32" }
}

Note: The "type" field is optional and ignored - types are inferred from compiler context.

JSON (Sloppy format accepted)

{ "x": "0x0001", "y": "1000" }

YAML (Optional)

witness:
  x: "0x0001"
  y: "1000"
  # Comments allowed!

Features

• Full backward compatibility with existing JSON files
• YAML sections support comments and documentation
• Intelligent format detection: tries JSON first, then YAML
• Type information from compiler (no manual type definitions needed)
• Support for ignored sections in YAML for documentation

Testing

• 8 new YAML unit tests in src/serde.rs
• 58 existing integration tests pass unchanged
• All old JSON tests continue to work (100% backward compatible)

CI Testing

• All passed

Dependencies

• Added serde_yaml = "0.8" to Cargo.toml (compatible with rustc 1.79.0+)

Breaking Changes

None. All existing code continues to work without modification.

Migration Guide

No migration required. Existing JSON files work as before. YAML support is optional.

[coremoon]

You can see here that all CI runs went through on my fork:

I don't understand why it's not after the merge.

[uncomputable]

Thank you for your PR. There seems to be a conflict with the recently merged #187. CI seems to be blocked on a rebase.

[coremoon]

Regarding the timeline with #187:

#186 was opened Dec 24, I started #192 based on a pre-#187 fork (merged Dec 27), and opened #192 Dec 29.

#192 fully implements #186 (optional param/witness modules) - the code change from .ok_or(Error::ModuleRequired(...)) to if let Some(...) proves both modules are now optional. It also implements #177 (witness format improvements).

#187 was parallel work on #186. The team can choose which approach to use.

Happy to address any technical questions.

[apoelstra]

#192 fully implements #186 (optional param/witness modules) - the code change from .ok_or(Error::ModuleRequired(...)) to if let Some(...) proves both modules are now optional.

I complained about your LLM-generated diff and proposed a new one, which I implemented in #187, which is simpler and more complete. It is already merged (and was merged a week before your most recent comment saying the team can "choose which approach to take").

It also implements #177 (witness format improvements).

We are not going to implement a YAML witness parser. I provided some reasoning in this comment. I'm going to close this because I think both changes in this PR are going nowhere.