Erlang didn't introduce the actor model, any more than Java introduced garbage collection. That model was developed by Hewitt et al. in the 70s, and the Scheme language was developed to investigate it (core insights: actors and lambdas boil down to essentially the same thing, you really don't need much language to support some really abstract concepts).
Erlang was a fantastic implementation of the actor model for an industrial application, and probably proved out the model's utility for large-scale "real" work more than anything else. That and it being fairly semantically close to Scheme are why I like it.
Claude code already works as an agent that calls tools when necessary so it’s not clear how an abstraction helps here.
I have been really confused by langchain and related tech because they seem so bloated without offering me any advantages?
I genuinely would like to know what I’m missing.
That said, a lot of current agent workloads are I/O bound around external APIs. If 95% of the time is waiting on OpenAI or Anthropic, the scheduling model matters less than people think. The BEAM’s preemption and per process GC shine when you have real contention or CPU heavy work in the same runtime. Many teams quietly push embeddings, parsing, or model hosting to separate services anyway.
Hot code swapping is genuinely interesting in this context. Updating agent logic without dropping in flight sessions is non trivial on most mainstream stacks. In practice though, many startups are comfortable with draining connections behind a load balancer and calling it a day.
So my take is: if you actually need millions of concurrent, stateful, soft real time sessions with strong fault isolation, the BEAM is a very sane default. If you are mostly gluing API calls together for a few thousand users, the runtime differences are less decisive than the surrounding tooling and hiring pool.
Elixir just feels… Like it’s a load of pre-compile macros. There’s not even a debugger.
A note on terminology: Throughout this post I refer to "the BEAM." BEAM is
the virtual machine that runs both Erlang and Elixir code, similar to how the
JVM runs both Java and Kotlin. Erlang (1986) created the VM and the
concurrency model. Elixir (2012) is a modern language built on top of it with
better ergonomics. When I say "BEAM," I mean the runtime and its properties.
When I say "Elixir," I mean the language we write.
mccoyb•9h ago
> TypeScript/Node.js: Better concurrency story thanks to the event loop, but still fundamentally single-threaded. Worker threads exist but they're heavyweight OS threads, not 2KB processes. There's no preemptive scheduling: one CPU-bound operation blocks everything.
This cannot be a real protest: 100% of the time spent in agent frameworks is spent ... waiting for the agent to respond, or waiting for a tool call to execute. Almost no time is spent in the logic of the framework itself.
Even if you use heavyweight OS threads, I just don't believe this matters.
Now, the other points about hot code swapping ... so true, painfully obvious to those of us who have used Elixir or Erlang.
For instance, OpenClaw: how much easier would "in-place updating" be if the language runtime was just designed with the ability in mind in the first place.
znnajdla•51m ago
It matters a lot. How many OS threads can you run on 1 machine? With Elixir you can easily run thousands without breaking a sweat. But even if you need only a few agents on one machine, OS thread management is a headache if you have any shared state whatsoever (locks, mutexes, etc.). On Unix you can't even reliably kill dependent processes[1]. All those problems just disappear with Elixir.
[1] https://matklad.github.io/2023/10/11/unix-structured-concurr...