How about just `Promise`, following `String`, `Number`, `RegExp`, etc.? (I tend to agree with Tab that both #a and #b should return a new promise. But we do need an easy coercion function, as Mark emphasizes.)
On Aug 21, 2013, at 18:31, "Mark S. Miller" <[email protected]<mailto:[email protected]>> wrote: On Wed, Aug 21, 2013 at 3:16 PM, Tab Atkins Jr. <[email protected]<mailto:[email protected]>> wrote: On Wed, Aug 21, 2013 at 1:57 PM, Mark S. Miller <[email protected]<mailto:[email protected]>> wrote: > Excellent excellent! It seems we are in agreement and clarity on all > terminology issue, and on almost complete agreement on substantive issues. > The only remaining issue is whether either of the following expressions > always return a fresh promise, and if they are exactly equivalent: > > a) Promise.resolve(v1) > b) new Promise(r=>r.resolve(v1)) > > When v1 is a promise, > x) I prefer that #a return v1 and #b return a fresh promise that adopts v1. > y) You prefer that both #a and #b return a fresh promise > z) The fewest feasible allocations would have both return v1. > w) I do not expect anyone will want #a to return a fresh promise and #b to > return v1. > > We both agree that if we settle on either #y or #z, then #a and #b are > equivalent. Otherwise they are equivalent up to this issue. > > The reason I prefer that #b return a fresh promise is that it is surprising > for a "new" expression to return something other than a fresh object. I think it's super bizarre for a class static to act differently from the trivial desugaring to the same-named instance method. (In this case, it's not *quite* an instance method, but close enough. ^_^ It would be an instance method if we weren't caring about capability grants.) > The reason I prefer #a is that the primary use case for #a is coercion -- > given possible promise v1, gimme a guaranteed genuine promise that > designates the same (possibly eventual) non-promise. See calls to the Q() > function at http://wiki.ecmascript.org/doku.php?id=strawman:concurrency and > http://es-lab.googlecode.com/svn/trunk/src/ses/contract/ (which corresponds > to http://research.google.com/pubs/pub40673.html ). These calls are numerous > and necessary, and sufficiently frequent that the extra transient allocation > in the typical case will be a noticeable cost. That's reasonable, but we should do it with a different function that just promotes things into promises, Good idea. As a coercing function, a natural name is Promise.as(v1). Also, as a common coercer, brevity is a virtue. or leave it to library code when they need it. (We don't, for example, have such an operation for Array/Map/Set, though I have used such an operation before.) ~TJ -- Cheers, --MarkM _______________________________________________ es-discuss mailing list [email protected]<mailto:[email protected]> https://mail.mozilla.org/listinfo/es-discuss
_______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
