Eclipse Fastbelt

Eclipse Fastbelt provides a toolkit for implementing formal languages, in particular domain-specific languages (DSLs), on the Go platform. High performance and low resource consumption on large workspaces are the primary design goals. The scope includes:

• A grammar language for defining concrete and abstract syntax, with generators that derive lexers, parsers, and type definitions from it
• Infrastructure for processing language documents: cross-reference resolution, scoping, indexing, validation, type checking, and parallel workspace builds, with customization points for all of these
• A library for using language implementations programmatically, e.g. in command-line tools, code generators, and automation services
• Exposure of language services through standard protocols, such as the Language Server Protocol (LSP) for editors and the Model Context Protocol (MCP) for AI agents, and further support for AI-assisted work with languages built on the toolkit
• Delivery of language implementations as native executables and for web environments via WebAssembly (WASM)
• Supporting tools for language developers: command-line interface, project scaffolding, testing utilities, editor support for the grammar language, examples, and documentation

Eclipse Fastbelt does not include text editing functionality, which is left to editors that support LSP. General-purpose tooling for the Go programming language, AI models, and general-purpose AI agents are also out of scope.