April 10 2014 Meeting Notes

[Brendan Eich]

Mark S. Miller wrote:
>
>
>     BTW, return() should be idempotent. Is it?
>
>
> Since .return takes an argument whose value is observable, I think not.
>
> Hmmm. This is interestingly similar to multiple calls to resolve.

Yes, and note that Python's generator.close (no return value parameter, 
recall it throws a built-in exception, GeneratorExit, at the generator 
iterator) is idempotent. Calling it on a closed generator is a no-op.

This may be important for optimizability. Allen's speculation is that 
JITs can sort out early from "done" loop termination paths and 
maybe-call return only in the early cases, but I'm not so sure.

/be