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author-code

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Conventions for authoring Rust code in the Dada compiler. Use when writing or modifying Rust code, adding functions, or making implementation changes.

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Authoring Code in Dada

Code Style

  • Match local conventions — mimic the style of the file you're editing
  • Use existing utilities — check for helper functions before writing new ones
  • Check dependencies first — never assume a library is available; verify in Cargo.toml
  • Follow existing patterns — look at neighboring code and match its style

Documentation

When to document

  • Complex functions encoding Dada's semantics need thorough documentation
  • Self-evident code — simple utility functions don't need extensive comments

Documentation pattern

  • Use doc comments (///) with high-level explanation
  • Include concrete Dada code examples showing the feature being implemented
  • Use inline comments referencing back to the examples
/// Type checks a method call expression like `obj.method(args)`.
///
/// # Example
/// ```dada
/// let p = Point(x: 10, y: 20)
/// p.distance(other)  # <-- we are type checking this
/// ```
///
/// The method resolution follows these steps:
/// 1. Determine the type of the receiver (`p`)
/// 2. Look up the method in the type's namespace
/// 3. Check argument compatibility
fn type_check_method_call(...) {
    // Step 1: Get receiver type (Point in our example)
    let receiver_ty = self.type_of(receiver);

    // Step 2: Resolve method - this handles the lookup of `distance`
    // in the Point type's method table
    let method = self.resolve_method(receiver_ty, method_name)?;
}

Insight Comments (💡)

Use 💡 comments to capture non-obvious constraints and reasoning for future sessions.

Format

  • Preamble comment on functions: explain the overall algorithmic or architectural choice
  • Inline comments at the start of logical blocks: explain reasoning for that block
  • Before modifying code with 💡 comments: pause and consider whether the reasoning affects your planned changes

Decision boundaries

Annotate non-obvious decisions — skip self-explanatory code:

  • ❌ // 💡: Using a loop to iterate through items
  • ✅ // 💡: Using manual iteration instead of map() to handle partial failures gracefully

Document constraint-driven choices:

  • ❌ // 💡: Using async/await for the API call
  • ✅ // 💡: Using async/await because this API has 2-second response times that would block the UI

Document tradeoffs and alternatives:

  • ✅ // 💡: Using Redis instead of in-memory cache because we need persistence across server restarts

Capture consistency requirements:

  • ✅ // 💡: Using Result<T, E> pattern to match error handling in auth.rs and database.rs modules

Guidelines

  1. Focus on decisions with alternatives — if there was only one way to do it, don't annotate
  2. Update annotations when modifying code — ensure reasoning still matches implementation
  3. Be concise but specific — future sessions should understand the decision quickly

Error Handling

  • Use diagnostics infrastructure from dada-ir-ast
  • Provide helpful error messages with source spans
  • Follow existing error formatting patterns

References

  • Crate-level rustdoc — each crate has docs/overview.md included via #![doc = include_str!(...)]
  • Run cargo doc --open to browse implementation docs