Array comprehension syntax
brendan at mozilla.org
Sat Sep 22 09:24:29 PDT 2012
Jason Orendorff wrote:
> I'm sorry for the confusion here. I didn't mean to propose adding
> for-each-in to ES6. That would indeed be awful. I just meant that
> SpiderMonkey cannot necessarily drop this extension. So if the ES6
> syntax and SpiderMonkey's syntax can't coexist, it will be a problem
> for us.
Not to bother es-discuss too much, but in case there's interest:
I do hope we can retire 'each' from SpiderMonkey at some point.
Supporting it in comprehensions has a cost. Your example:
[x for each(x in obj).y of z]
can't be parsed without error given our current for-each implementation,
and backtracking and restarting with 'each' not contextually meaningful
I don't expect a lot of SpiderMonkey- (and Rhino-) specific code will
break, so making this an error when we support ES6 may be the best way.
Pull the bandage off quickly!
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