It amazes me to no end that CML-style concurrency is not used more often. (Even though Go is sort of almost there) I have been using guile fibers for some time

It amazes me to no end that CML-style concurrency is not used more often. (Even though Go is sort of almost there) I have been using guile fibers for some time, and it is a marvel! Not only can I write most code as if it was single threaded, but I can mix fibers code with pthreads and use fibers message passing when I need it.