moonbit-template: Instructions file for Codex

MoonBit Project

This is a MoonBit project.

Quick Commands

just           # check + test
just fmt       # format code
just check     # type check
just test      # run tests
just test-update  # update snapshot tests
just run       # run main
just info      # generate type definition files

Project Structure

• moon.mod.json - Module definition
• moon.pkg - Package dependencies (per directory)
• *.mbt - Source files
• *_test.mbt - Blackbox test files
• *_wbtest.mbt - Whitebox test files
• *.mbt.md - Doc test files
• *.mbti - Generated type interfaces (auto-generated by moon info)

Coding Convention

• Each block is separated by ///|
• Use moon ide commands for code navigation (prefer over grep)
• Use moon doc '<Type>' to explore APIs before implementing
• MoonBit code uses snake_case for variables/functions (lowercase only)
• UpperCamelCase for types, enums, and enum variants
• nobreak (not else) for functional for-loop exit values
• No return needed — last expression is the return value
• No try needed for error propagation — automatic (unlike Swift)
• Type parameter comes after fn: fn[T] foo(x: T) -> T
• Legacy function_name!(...) and function_name(...)? are deprecated

Tooling

• moon fmt - format code
• moon info - update generated package interfaces (.mbti)
• moon test - run tests. Use moon test --update to update snapshots.
• moon check --deny-warn - type check with warnings as errors
• moon doc '<query>' - discover APIs (more accurate than grep)
• moon ide peek-def <Symbol> - show symbol definition
• moon ide find-references <Symbol> - find all references

Before Commit

just release-check  # fmt + info + check + test