migrating `let' and `const'
brendan at mozilla.com
Wed Nov 16 11:02:02 PST 2011
On Nov 16, 2011, at 3:05 AM, Andy Wingo wrote:
> Hi again,
> Please excuse my ignorance, but:
No problem, we did not talk about how opt-in works.
> On Tue, 2011-11-15 at 07:41 -0800, Brendan Eich wrote:
>> To quote Waldemar from
>> "It's a judgment call, and I'd take these on a case-by-case basis.
>> For const and let, I see little harm in browsers allowing them now in
>> strict mode with the purely non-hoisting (C++-like) scoping rules,
>> particularly if they complained when you accidentally declared a
>> variable twice directly in the same block."
> So the current idea is that ES.next has different syntax and semantics,
> and so in general the strategy would be to offer <script type="harmony">
> and otherwise some form of "transpilation".
Right ("harmony" is a placeholder, the likely minimum but not best form would be type="application/ecmascript;version=6").
> But you are also proposing to move some ES.next features into the
> existing ES5.1 strict mode already provided by implementations?
No. Rather, Harmony (which is opt-in per above) is based on ES5 strict.
Compiling from ES.next to ES5 is doable but it may not match the "transpiling" (ugly word) definition.
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