Gleam is a small statically typed functional language that compiles to Erlang and runs on the BEAM. If you write Go, you already have most of the mental model that matters: a tiny language, explicit errors, and concurrency as the main event. What changes is that the concurrency is enforced rather than recommended, and the type system follows you into it.
The examples below are lifted from a real BEAM-native agent harness written in Gleam, so they're what the idioms actually look like in production rather than