- Facebook: spam filter implemented in an efficient data access language/tool called Haxl: https://engineering.fb.com/2014/06/10/web/open-sourcing-haxl-a-librar

- Facebook: spam filter implemented in an efficient data access language/tool called Haxl: https://engineering.fb.com/2014/06/10/web/open-sourcing-haxl-a-library-for-haskell/ https://engineering.fb.com/2014/06/10/web/open-sourcing-haxl... - WhatsApp: famous for being written in Erlang, a functional programming language, and processing more messages a day than the entire global SMS network with a team of 50 backend engineers - Discord: handling extreme amounts of chat/call traffic using Elixir, another functional programming language based on the same tech as Erlang - Telephones: telephone switches from Ericsson (and in fact, internet switches from Cisco) use Erlang - Docker: core virtualization component for macOS (hyperkit) written in OCaml - Amazon EC2: another core virtualization component of all computes, parts of the Xen hypervisor, written in OCaml