> Almost all of the bespoke code is written in Python, but the message-passing architecture of the system and the approach to managing availability was directly inspired by reading about Erlang (in particular your book).

This approach is pretty interesting - I’d love to read about implementing Erlang-style availability in other languages.

In my experience, the message passing architecture of the NHS system almost exclusively uses Paper.

and fax.

I have been watching this for a while: the Chez Scheme concurrency engine

https://github.com/becls/swish

Another in Gambit Scheme, but it hasn't been touched in a while:

https://github.com/mindpool/gambit-termite