On Fri, Apr 25, 2014 at 8:48 AM, Rick Waldron <[email protected]>wrote:
> On Fri, Apr 25, 2014 at 11:16 AM, Mark S. Miller <[email protected]>wrote: > >> Hi Domenic, that's a long thread. Could you summarize, or point at a very >> small number of messages on that thread that get the point across? Thanks. >> > > Mark, > > This is the specific post we discussed at the last meeting: > http://esdiscuss.org/topic/yield-desugaring#content-29 > > (It may not be the one Domenic is referring to, but it's relevant to this > discussion) > Ok, the point of that post still seems well summarized by the example at the end for_each_n(x => console.log(x), iter, 10); // first 10 > for_each_n(x => console.log(x), iter, 10); // next 10 > And the points > In summary my problems with close() are these: > 1. It attempts to provide a reliable finally for unlimited-extent > activations, when we can't do that. > 2. It complicates the mental model of what happens when you yield. > 3. It makes common sugar like for-of inappropriate for some uses of > generator objects. IIRC, on wednesday at tc39, when Brendan presented this, I found it compelling. On thurs (when Brendan was absent) when this came up again, I flipped because of the following argument: Given that for/of comes to be understood to use up its iterable's iterator, when the iterable is the iterator and you desire not to use it up, don't use for/of. Use for(;;) instead, which is easy enough and makes it more explicit what you are and are not doing in the iteration. Regarding the points: #1 yes, we cannot provide one that's reliable, so let's not claim that it is reliable. #2 yes it does. I acknowledge that this is a genuine cost. #3 for those rare cases where it is inappropriate, like this example, better not to use a for/of anyway to make the unusualness of this code's purpose more explicit. -- Cheers, --MarkM
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