arrow function syntax simplified

Dmitry Soshnikov dmitry.soshnikov at
Sun Apr 1 01:46:48 PDT 2012

On Apr 1, 2012, at 1:40 AM, Dmitry Soshnikov wrote:

> On Apr 1, 2012, at 1:22 AM, Axel Rauschmayer wrote:
>>> On Apr 1, 2012, at 12:34 AM, Axel Rauschmayer wrote:
>>>>>> Ah, good. But one can use the above (pseudo-)desugaring to predict the behavior of arrow functions, right? That is, there is no observable difference.
>>>>> There is, again, the difference in terms of delegation to the target's [[Construct]] in case of a bound function, see the spec ("bound" per ES5, of course, since, as Brendan notices, it's not just a syntactic sugar, but a new special type of functions).
>>>> OK. Ignoring [[Construct]] and .prototype, any other differences?
>>> Well, "ES5-bounds" also do not have `prototype' property, but delegate to the target's `prototype'. However, yes, there is the (main) difference in respect of supporting TCP (if I understand correctly, since had no time to follow the complete thread) -- return and break/continue jumps to the parent frame instead of working with the function itself.
>> Arrow functions do not adhere to TCP. Everything you need to know is here:
> Yes, thanks I've read it. But probably I misunderstood the description, but what then is the following mean?
> "... bind return in the Block body case so it returns from the immediately enclosing arrow function, and preclude breakand continue from referencing statements outside the immediately enclosing arrow function."
> Isn't it for supporting TCP? (sorry if it was already discussed and explained before, that's said, unfortunately hadn't time to join earlier)

Ah, ignore this, I skipped the last note in the Rationale section related to TCP.


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