Erlang is used at WhatsApp. One of the interesting things there is that for the amount of users and messages handled they had a very small backend team. They ha

Erlang is used at WhatsApp. One of the interesting things there is that for the amount of users and messages handled they had a very small backend team. They have credited Erlang and its features as one of the keys to their success. It means less code (mostly related to minimal impedance mismatch from language to problem domain), debug-ability, reliability, fault tolerance, less ops overload and so on. I personally find it much easier to navigate and fix bugs in an Erlang code base than in the equivalent C++/Java/C# one. It mainly boils down to how state is updated. When I see NewState = update(Value, State) it is clear what is happening. In OO code, I usually need to remember what object inherits from, what are is the instance state so far (what other members have been called) and how it got there. I find that much harder to handle, for example.