On Jun 8, 2012, at 3:58 PM, Brendan Eich wrote: > Allen Wirfs-Brock wrote: >> It may well be that the initial Expression of the ArrayComprehension >> productions should be an AssignmentExpression in order to avoid commas. > > This is just a draft-spec grammar bug. What I implemented in SpiderMonkey > many years ago is what is grammatically necessary: AssignmentExpression. > Otherwise you have not only a readability problem as Jay wrote, but a real > problem in top-down parsers deciding whether you are in an array initialiser > or array comprehension. Bottom up parsers can cope but practical > implementations are all top-down.
What do you think about the expression following the of or if of a comprehension, assuming we are going to be paren-free. Both can be in a trailing position within a comprehension. I don't think there are any parsing issue with them, but they represent similar readability issues: [ i for i of foo, bar] [i for i of foo if i!=="bar", false] Assignment expression would eliminate that reability issue. Of course, so would mandatory parrens. Allen _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
