Mark S. Miller wrote:
On Tue, Jul 16, 2013 at 10:54 AM, Claus Reinke
<[email protected] <mailto:[email protected]>> wrote:
// this doesn't work
function* generator(){
[1,2,3].forEach( function(x){ yield x } )
}
This would make generators deep, violating the
non-interleaving assumptions
of intermediate callers on the call stack. This is why we accepted
generators only on condition that they be shallow. We knew at
the time that
this privileges built-in control structures over user defined
ones. The
alternative would have been to omit generators completely. We
agree that
shallow generators were worth it, despite this non-uniformity.
While I understand the compromise, and the wish to get in some form
of generators anyway, the discrimination against user-defined control
structures troubles me deeply.
Troubles me too. As of ES6 the only possible alternative would be to
remove generators from the language. I can't see that happening.
That would be somewhere between "making the perfect the enemy of the
good" and "cutting off your nose to spite your face".
If we want call/cc (plus macros to sugar it into usability), there's the
door -- it ain't in JS outside of Rhino, and (for good reasons you
adduce) it won't be added.
But we have good use cases for generators, including to implement
iterators independent of async. programming.
For async we're looking at defer/await for ES7.
This is how living languages evolve. Sorry to preach to the choir (I
hope :-P).
/be
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