When there is no type hierarchy you don't have to manage the type hierarchy.
Rule 1. You can't tell where a program is going to spend its time. Bottlenecks occur in surprising places, so don't try to second guess and put in a speed hack until you've proven that's where the bottleneck is
Narrowness of experience leads to narrowness of imagination
If POSIX threads are a good thing, perhaps I don't want to know what they're better than.
Not only is UNIX dead, it's starting to smell really bad.
Productivity is most important by engineering management rules, but enjoyment is most important for engineers. One stems from the other.