[coldtea]

>Guess I should have said "blocking I/O"? I thought it was a given that a single threaded language wouldn't magically inject some kind of concurrency around tight loops or CPU intensive tasks.

Well, Erlang (and Elixir) does just that -- it's preemptive, and implicitly yields under the covers even in loops.

>Node.js people don't really think that sort of thing is "non blocking", do they?

Judging from forum threads and blog posts, a lot of them do, especially web programmers not familiar with blocking and non-blocking that only know that "Node is webscale".