Erlang

One of the more obscure languages I've had reason to program in (indeed, have taken a course in) is Erlang. Erlang is a declarative real-time language, which owes much to Prolog and ML. It was originally developed in the 1980s as a more modern replacement for PLEX, but it never managed to topple the huge installed PLEX codebase, so Ericsson telephone exchanges are still programmed in PLEX, albeit a somewhat more developed and modernised version. On the other hand, Erlang is also still a living language with new releases coming out every few months.

Anyway, I was sent this old demo video, where Bjarne Däcker & Co show off the features of the new language. It's a marvellous document of its time, so if you were involved in CS research twenty years ago, watch and get nostalgic!