Day 1 meeting notes

Brendan Eich brendan at
Thu Jul 29 01:43:03 PDT 2010

On Jul 29, 2010, at 1:20 AM, Peter van der Zee wrote:

> On Thu, Jul 29, 2010 at 2:06 AM, Waldemar Horwat <waldemar at> wrote:
> Error prone:  for (x in Iterator.values([1,2,3,4,5])) vs. likely
> programming error for (x in [1,2,3,4,5])
> Waldemar:  If they are separate concepts, using the same for-in syntax
> for iteration and enumeration is too error-prone.  If you intend to
> iterate on object Foo but accidentally pass in a Foo that's not an
> iterator, you'll get its property names instead of a visible error.
> It's particularly insidious with arrays.
> Would a keyword "as" be a sufficient alternative to use as an iteration operator in this sense? "as" would (I think?) not be allowed as an identifier in that position so it wouldn't have to be added to the reserved word lists. Because of that, I don't see a parser problem with it either.
> Maybe, for somewhat better semantics, the order could be switched (`iterator as key` would make slightly better sense compared to `key as iterator`. I'm okay with either way since the switch would mean slightly more complicated syntax, eg. the var statement).

The whole "fatal flaw" claim is Waldemar's opinion, but we've shipped for-in with (unstratified) meta-programmability since 2006 (Firefox 2) and Python has had it for years. Where are all the corpses?


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