I agree. I've found Go channels to be disappointing in practice. There's lots of PR but little criticism of something so key. The fact that they are implemente

I agree. I've found Go channels to be disappointing in practice. There's lots of PR but little criticism of something so key. The fact that they are implemented using mutexes is, from my admittedly limited, non-concurrency-expert perspective, inexplicable. The simplest use case, an unbuffered channel, should be trivial to implement using CAS. There's a bunch of research on implementing robust queues using CAS. Then there are the various ugly edge cases: Closing a closed channel is an error (now you have to implement your own refcounting implementation if you want to hand out a single channel to multiple consumers), receive on nil channel blocks (means you can't use nil as a signal to mean "I've closed the channel"), etc. I really like GCD's style of enqueueing concurrent tasks, which I think is a concurrency model that often works more naturally than channels. A major difference between GCD and goroutines is that you can specify what queue to use. I'm looking forward to see what they come up with for Swift.