moonbitlang

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.

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.

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.

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.

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.

Work with Office/OOXML documents — Excel .xlsx spreadsheets and Word .docx files — by running this repo's CLIs on the WebAssembly backend, a memory-safe sandbox with no native document libraries. Use it to generate a spreadsheet or Word document, turn CSV/table data into .xlsx, author a .docx (headings, styled text, links, images, lists, tables) from a JSON op script, read a document's structure/text/elements as JSON, convert a .docx to HTML or Markdown, extract images, or check that a file is structurally valid. Reach for this instead of openpyxl / ExcelJS / python-docx / pandoc / LibreOffice.