I tried making a CSP library for C. It was not very pleasant. At best you end up with something slightly significantly less safe than POSIX threads, but now wit

I tried making a CSP library for C. It was not very pleasant. At best you end up with something slightly significantly less safe than POSIX threads, but now with message passing. While C is an extreme example it's certainly not true that all languages can add CSP/actors/whatever in an appetizing form through a library. Anyway, there's a reason the phrase "tacked-on" has such negative connotations.