Yeah - the technology used is a seperate concern to their abilities as users (developers) of that technology and the effectiveness at handling the scale.

I, for example, have always said that I am more than capable of writing code in C that is several orders of magnitude SLOWER than what I could write in.. say Python.

My skillset would never be used as an example of the value of C for whatever

Erlang is uniquely suited to chat systems out of the box in a way that most other ecosystems aren't. Lightweight green threads via the BEAM vm, process scheduler so concurrent out of the box, immutable data structures, message passing as communication between processes.

There's nothing unique about Erlang. I have nothing against it but other companies have built messaging systems using other platforms that work as well or better than WhatsApp.

Examples please.

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