I've also linked to js-csp, a JS library obviously not implemented using macros.
I can also find other examples of implementation as libraries, but I have no experience with them:
- Scala: https://github.com/rssh/scala-gopher
- F#: https://github.com/Hopac/Hopac
- C++: http://www.cs.kent.ac.uk/projects/ofa/c++csp/