Promise.cast and Promise.resolve

Kevin Smith zenparsing at gmail.com
Tue Jan 28 10:12:18 PST 2014


>
>
> My take is that the difference between "cast" and "resolve" is so
> subtle that I don't think it captures developer intention. In
> other words, if I see some code calling Promise.cast(otherPromise),
> I can't be sure that the developer made an intentional choice over
> Promise.resolve(otherPromise).
>

Note that `Promise.resolve(p)`, where p is a promise, does *not* return an
eventual for the eventual value of p.  Rather, it returns an eventual for
p, literally.  Promises should be considered fully parametric (in other
words, nestable).

If you want to convert a maybe-promise into a promise, then you want `cast`.
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