too-early feedback implementing ECMA6 array comprehension syntax
brendan at mozilla.org
Fri Jun 8 15:58:01 PDT 2012
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.
Jay, thanks for pointing this out.
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