moonbitlang

Guides agents through complete, maintainable MoonBit bindings for C/C++ libraries, from upstream source survey through vendoring, safe API design, documentation tests, and ASan validation. Use when creating or hardening MoonBit native FFI bindings, wrapping C APIs, vendoring C sources into native-stub, or turning a C library into a MoonBit package.

Guide for writing, refactoring, and testing MoonBit projects. Use when working in MoonBit modules or packages, organizing MoonBit files, using moon tooling (build/check/run/test/doc/ide etc.), or following MoonBit-specific layout, documentation, and testing conventions.

Guide for migrating OCaml projects, libraries, modules, and test suites to idiomatic MoonBit. Use when translating OCaml code to MoonBit, planning a large OCaml-to-MoonBit port, preserving byte/string-heavy behavior, replacing OCaml variants/records/exceptions/refs/arrays, mapping OCaml APIs to MoonBit packages, or building verification and test strategy for a migration.

Create formal spec-driven MoonBit APIs and test suites. Use when asked to set up a spec.mbt, spec-driven tests, or a formal contract-first workflow (e.g., "set up a formal spec & test suite for Yaml in MoonBit"), including moon.mod.json/moon.pkg.json scaffolding and guidance to implement in separate files.

Use this skill when the user needs help solving MoonBit language, code, compiler diagnostic, package, toolchain, backend, FFI, test, or "does MoonBit have X?" questions. Use it even when MoonBit is only implied by .mbt files, moon.mod.json, moon.pkg.json, moon commands, wasm/js/native targets, or mooncakes packages. This skill helps choose the right MoonBit source of truth, discover APIs with moon ide, avoid stale assumptions, and validate fixes.

Extract formal spec and comprehensive test suites from existing MoonBit implementations. Use when asked to "extract spec from implementation", "generate tests from code", or "create spec-driven tests for existing package". Analyzes existing code to produce spec.mbt with `declare` keyword stubs and organized test files (valid/invalid).

Guide for writing, refactoring, and testing MoonBit projects. Use when working in MoonBit modules or packages, organizing MoonBit files, using moon tooling (build/check/run/test/doc/ide etc.), or following MoonBit-specific layout, documentation, and testing conventions.

Guide for migrating OCaml projects, libraries, modules, and test suites to idiomatic MoonBit. Use when translating OCaml code to MoonBit, planning a large OCaml-to-MoonBit port, preserving byte/string-heavy behavior, replacing OCaml variants/records/exceptions/refs/arrays, mapping OCaml APIs to MoonBit packages, or building verification and test strategy for a migration.

Guide for writing MoonBit bindings to C libraries using native FFI. Use when adding extern "c" declarations, writing C stubs with moonbit.h, configuring native-stub and link.native in moon.pkg, choosing

Refactor MoonBit code to be idiomatic: shrink public APIs, convert functions to methods, use pattern matching with views, add loop invariants, and ensure test coverage without regressions. Use when updating MoonBit packages or refactoring MoonBit APIs, modules, or tests.

Use when writing or refactoring proof-carrying code in MoonBit, especially for Why3-backed specifications, abstraction functions, representation invariants, proof assertions, recursive verified data structures, or reducing trusted proof bridges.

Use when maintaining the moonbitlang/moonbit-docs repository, including Sphinx docs under next/, MoonBit examples under next/sources/, error-code documentation, gettext translations, or the moonbit-tour web app. This skill routes to focused references and validation commands for repo maintenance work.

Write and maintain Rust CLI/integration tests with snapbox 0.6+ using command assertions, inline snapshots, and minimal wildcard/redaction patterns. Use when replacing manual `get_output` parsing, stabilizing cross-platform snapshots, or refining existing snapbox assertions.

Add a new blog post to this Docusaurus site from a staging folder.