Why Erlang’s BEAM VM Is Unique: Garbage Collection and Async IO

Q1. What makes the Erlang VM (BEAM) special compared to other VMs?

Eric Merritt: In many systems like Java, the garbage collector must scan the entire heap, but BEAM uses the actor model, allowing garbage collection only for processes that need it:

If a process is not running, no collection is needed.

If a process has terminated before the GC runs, no collection is needed.

If a process needs to be reclaimed, only that single process is terminated.

BEAM also provides efficient built‑in asynchronous I/O, making async programming straightforward.

Q2. What was the design goal of Joxa?

Eric Merritt: After DSLs solved a problem for him, he found that Erlang did not integrate well with DSLs, so he created Joxa on top of Erlang and BEAM, which turned out to be the right decision.

Q3. What are your thoughts on Elixir?

Eric Merritt: He sees Elixir as an ambassador for Erlang, making it easier to learn, but remains neutral because its macro system is inconsistent and its mutability could improve.

Q4. What is your view on laziness in programming languages?

Eric Merritt: Laziness is a practical idea that has existed in functional programming for decades; it becomes more valuable if better tools for detecting and debugging space leaks emerge.

Q5. Could a new Erlang‑based language be created using a Hindley‑Milner type system without breaking Erlang semantics?

Answer: Yes, he is planning such a project, though timing is uncertain. The challenge lies in reconciling Erlang’s untyped runtime with a typed system; languages like ROY or Clojure offer useful references.

Q6. Should the Erlang VM add algebraic data types, or are records and tagged tuples sufficient?

Eric Merritt: Type systems relate more to the language than the VM; adding algebraic types can enable more optimizations, but a mature typed language running on the VM offers limited benefit.

Q7. Are there other languages or technologies you are watching?

Eric Merritt: He is interested in micro‑kernels such as JVM‑based OSv, Mirage for OCaml, BSD Rump Kernels, as well as the Nix package manager, NixOS, and HashiCorp’s Atlas.