On Jan 22, 2008, at 12:14 PM, Lars T Hansen wrote:
> Ergo some implementations will have this
> improvement; users will start depending on it; other implementations
> will follow; and the explicit syntax is useful *only* as an assert
> that the tail call can in fact take place, and will be useful only to
> people who know about it and value it. Like type annotations, I
> guess.
Ding ding ding....
> IMO, the best design is that (a) a call that is syntatically in tail
> position is executed as a tail call when that is possible, but as a
> non-tail call when type conversions or type checking interferes, and
> that this happens without the programmer having to think about it, and
> (b) an annotation ("goto",
"tail" ;-)
> whatever) can be used to check that the
> tail call is in fact possible, and it will cause an error (at compile
> time in strict mode, possible) if that is not possible. Thus we have
> tail call annotations like we have type annotations; people use them
> if they feel that provides benefit. For everyone else it "just works
> except when it doesn't" -- again, exactly like typing.
This works for me. The desire for explicitude was well-intentioned
but misdirected. It has found its target: an optional syntax for
asserting a tail call. Thanks to all (esp. Jon Zeppieri for putting
the assertion idea down in the bug) for this discussion (it helped
crystalize things for me, at least).
/be
_______________________________________________
Es4-discuss mailing list
Es4-discuss@mozilla.org
https://mail.mozilla.org/listinfo/es4-discuss
