Erlang is a little-known programming language that has a lot of history and tremendous capabilities for building concurrent software.

Since it's not really a popular language, many times I get asked what's so good about Erlang and how I feel about using it for certain types of projects. This is my attempt at answering these questions.

Pros

Simplicity

Personally, this is one of the most valuable characteristics of a language. Not only is Erlang functional (one of the simplest existing programming languages paradigm), but it also has a very small set of syntactic primitives that you can use. Even the concurrent aspect of the language is done using just plain functions (with the exception of the receive primitive).

Erlang's simplicity also makes it very understandable and fun to work with.

Managing Concurrency & Failure

Erlang concurrent programs can be built, scaled and distributed with ease. Once you have the deployment and integration set up, scaling Erlang nodes and spawning new Erlang processes on different machines becomes easy. Erlang standard library provides easy-to-use functions for this very purpose, so reaching parallelism is not only cheap in terms of implementation but also elegant.

When it comes to program failures Erlang also has your back. When spawning new processes you are guaranteed to be notified about it to all the monitors and links that were established. This allows to re-spawn any failed process automatically, which is already part of the OTP standard library and the default way for structuring Erlang applications.

Mature community

One of the most important aspects to consider when trying to predict a technology's future is to check the what kind of community that technology is being supported and used by. We've all seen good technologies that end up being destroyed with useless and buggy features; this is usually what a toxic community does.

Erlang's community is small, mature and simplicity-driven, which protects it from being destroyed. This is why Erlang benefits and robustness has lasted this long.

Cons

Setup

Setting up, provisioning and deploying Erlang applications can be hard to understand and cumbersome. This is due to many reasons, one of the most important ones being the lack of a proper and unique package manager.

Also, the hot-reloading feature that Erlang provides by default is no longer applicable is nowadays containerization of applications. Instead of having to upload the new code and triggering a hot-reload, you would just start up an new container and stop the one that's currently running. The Docker-way of doing things differs a bit from the Erlang-way, so in some cases, you may have to apply some hack-ish behavior for deployments.

Types

Erlang is a dinamically-typed language, meaning that during the compilation phase you won't get any type errors. I've worked around strongly-typed languages for some time and I can say that not having the compiler type-check your programs is a huge downside. Even though with a static type checker errors in your programs are detected during development, Erlang's robustness and failure handling makes errors during runtime a lot less costly.

There's also some other tools that allow to type-check your Erlang programs during compilation, such as Dialyzer, but still lack many features and will not detect all the errors you may have, even when turning on all possible warnings. You might get a few errors that are helpful, but it will still miss many errors that can be checked at compile-time.

Conclusion

All-in-all, Erlang does an almost-perfect job at handling concurrency and the complexity involved when dealing with it, including error handling, concurrency guarantees and architectures robustness. Even though it lacks some very useful features used by many programming languages like a proper package manager and a static type-checker, it does not obfuscate its benefits.

Erlang might not be the right tool for every project, but it's definitely very practical and safe working with it which makes it worth considering it. Honestly, I love Erlang.