Introducing the Erlang Language Platform for Enhanced Development

In their presentation at Code BEAM Europe 2023, Roberto Aloi and Michał Muskała introduced the Erlang Language Platform (ELP), a new open-source project aimed at improving the development experience for Erlang programmers. ELP, designed at WhatsApp, draws inspiration from the Rust Analyzer project and acts as a scalable, IDE-first library for Erlang's semantic analysis. The platform implements support for the LSP protocol, functioning as a next-generation language server that enhances code writing, debugging, and maintenance. Aloi and Muskała discussed the limitations of existing tools within Erlang's OTP distribution, particularly their lack of resilience, poor error recovery, absence of metadata preservation, and insufficient flexibility with macros. ELP addresses these issues by providing a highly interactive, incremental, and parallel execution environment, optimized for modern IDE requirements. Written in Rust, ELP leverages deep integration with tools like Tree-sitter for parsing, ensuring full-fidelity representation of source code and facilitating fault-tolerant parsing. Features such as live diagnostics, built-in refactoring options, type annotations on hover, and inlay hints for parameter names highlight ELP's advanced capabilities. ELP has been in use at WhatsApp for a year and is available as open-source software on GitHub, with integrations for various build systems and editors, including VS Code and Emacs.