Introduction, comprehensions beyond arrays
brendan at mozilla.com
Fri May 10 11:36:57 PDT 2013
Jason Orendorff wrote:
> On Thu, May 9, 2013 at 11:42 PM, Mike Stay <metaweta at gmail.com
> <mailto:metaweta at gmail.com>> wrote:
> In Scala, this is desugared into
> expr1.flatMap(x =>
> expr2(x).flatMap(y => ...
> exprN(x, y, ...).map(z =>
> result(x, y, ..., z)
> Currently comprehensions use the same protocol as for-of statements,
> namely iterators. I think we definitely want them to use the same
> .map() is appealing, but to work with for-of statements, it would have
> to support break, continue, and early return, either using exceptions
> (like Scala's Breaks) or something new. Part of the appeal of the
> iterator protocol is that it doesn't complicate break/continue/return.
Agreed. JS ain't Scala.
Note for Mike Stay, in case it helps a bit (just syntax): we agreed to
use LTR order, so:
[for (x of expr1) for (y of expr2(x)) result(x, y)]
to shorten your example a bit.
> Separately, for the list: are arrow-functions lexically transparent to
> super and arguments? I hope so! For this kind of desugaring, if
> nothing else.
'super' like 'this' is lexical -- the outer function's same-named
an error. Perhaps we should change this to match the keywords. Allen?
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