Mailboxer:Early Detection of Erlang Communication Errors- Phil Trinder & Duncan P. Attard |Code BEAM

CodeSync · May 3, 2025, 1:00pm

This talk was recorded at Code BEAM Europe in October 2024. If you’re curious about our upcoming event, check https://codebebeameurope.com

The talk presents and demonstrates a new communication checking tool for Erlang codebases: Mailboxer.

If a developer annotates parts of an Erlang codebase with expected message types Mailboxer can statically detect many communication errors in the annotated processes. So errors like unreceived messages, some deadlocks, protocol violations, typos in message tags etc. Finding errors early in development reduces debugging and development times.

Existing session type checkers for Erlang and Elixir enforce channel, rather than mailbox, based communication. In contrast, Mailbox types check communication using idiomatic mailbox communication. Currently, Mailboxer targets Erlang, but the type theory and checking technology apply to other actor languages with mailboxes, so Elixir, Scala/Akka and others.

Erlang will be the first production language to benefit from a radically new communication-checking tool.

Comments welcome! View the code-sync tag for more Code Sync talks!

keyhan · July 2, 2025, 12:03pm

IMO it is nice idea to define pattern of process communication to eliminate errors and bugs,
mailboxer is that tool like dialyzer for communication checking,

nato · July 14, 2025, 9:23pm

Any open-source repos of this to take her for a spin? @duncanatt

duncanatt · October 7, 2025, 5:22am

@nato Sorry for the late reply, but we’ve been working on an online sandbox where devs can try out a very early version of Mailboxer. It’s a simple way to explore how the system works and see the kinds of communication errors it can statically rule out.

We’d love to hear your thoughts and feedback. Link: Mailboxer Demo.