BEAM There, Done That with Roberto Aloi & Michał Muskała on ELP, eqWAlizer and Erlang Tooling at WhatsApp - Part 2

Part two of two. Part one covered scale and operations; this one covers the tooling that keeps a large codebase navigable.

The practical recommendation from Roberto: download ELP from GitHub (WhatsApp/erlang-language-platform), run it against a project you maintain, and report what doesn’t work. External codebases surface issues that internal use never finds.

On the types question that often comes up: Michał’s position is that types and let it crash are complementary, not in tension. You can never statically verify everything in a dynamic language - the gap is exactly where supervision and recovery belong. Gleam’s stronger type system coexisting with BEAM fault tolerance is the clearest illustration of this.

The open sourcing reasoning is worth repeating: it’s not charity. Diverse use cases, diverse bug reports, and external contributors make the tools better faster than internal use alone ever would.