Building a Custom BEAM Virtual Machine: Understanding Erlang/Elixir's Concurrency Primitives

The article is a blog post adaptation of a Code BEAM Europe 2025 talk about creating a custom implementation of the BEAM virtual machine (which runs Erlang, Elixir, and Gleam). The author explores BEAM's core primitives - processes without shared state, message passing with selective receive, and process linking for supervision trees. The content explains ho