On Fri, May 10, 2013 at 12:36 PM, Brendan Eich <[email protected]> wrote: > Jason Orendorff wrote: > >> On Thu, May 9, 2013 at 11:42 PM, Mike Stay <[email protected] >> <mailto:[email protected]>> 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 protocol. >> >> .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.
I wouldn't want it to be! And I agree that it makes sense for the array comprehensions to match the for-of semantics. > 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. OK, thanks. I suppose that with the arrow-functions, the boilerplate load drops tremendously. Is the ES6 spec too far along to introduce some other construct that would desugar to the above, or is there still time to create a proposal? >> 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 keyword > meaning. > > 'arguments' per > http://wiki.ecmascript.org/doku.php?id=harmony:arrow_function_syntax is an > error. Perhaps we should change this to match the keywords. Allen? > > /be > -- Mike Stay - [email protected] http://www.cs.auckland.ac.nz/~mike http://reperiendi.wordpress.com _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
