>core.async: So the guys who built golang did it because they had this cool idea for creating coroutines using channels. However, since it required very low-level functionality to be part of the core of the programming language, they thought they'd have to design a brand new language to implement their idea. However, shortly after golang was released, Rich and some other clojure folks implemented the same feature in clojure as a totally ordinary external library, proving that the core of clojure was general enough to support this. And it wasn't just a gimmick: I use core.async every day and think it is better than golang's implementation.

It is very limited -- it was done by a single university student as his MS thesis -- but luaproc had added this functionality to Lua before Go even existed:

http://www.inf.puc-rio.br/~roberto/docs/ry08-05.pdf

Other M.S. theses from PUC have extended the library (in particular, adding support for sending tables) but it is otherwise unmaintained:

https://www.maxwell.vrac.puc-rio.br/30267/30267.PDF https://github.com/lmillanfdez/luaproc-master https://www.maxwell.vrac.puc-rio.br/35424/35424.PDF https://github.com/fernando-ala/luaproc---messaging-tables-a...