Re: The ES6 iteration protocol
I guess all built-in iterators return themselves for `Symbol.iterator` protocol. So they are all singletons. I described in detail where confusion/substitution of concepts happens in that analysis in the recent two comments. Dmitry On Mon, Apr 6, 2015 at 1:07 PM, joe joe...@gmail.com wrote: Regardless of what the spec says, you cannot avoid singleton iterators in real-world code. In my opinion, the spec should refrain from specifying when object creation happens within the iteration protocol, wait for the relevant code and contract patterns to develop and then include something in ES7. On Sun, Mar 29, 2015 at 12:08 AM, Dmitry Soshnikov dmitry.soshni...@gmail.com wrote: Good write up, although fresh vs singleton topic doesn't make sense, and doesn't reflect the spec. I responded on the gist. Dmitry On Sat, Mar 28, 2015 at 4:41 AM, Axel Rauschmayer a...@rauschma.de wrote: FWIW: I have written down my understanding of the ES6 iteration protocol (shaped by discussions I had on this mailing list). https://gist.github.com/rauschma/73e5f86a595b7709f39e -- Dr. Axel Rauschmayer a...@rauschma.de rauschma.de ___ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss ___ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss ___ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
Re: The ES6 iteration protocol
Regardless of what the spec says, you cannot avoid singleton iterators in real-world code. In my opinion, the spec should refrain from specifying when object creation happens within the iteration protocol, wait for the relevant code and contract patterns to develop and then include something in ES7. On Sun, Mar 29, 2015 at 12:08 AM, Dmitry Soshnikov dmitry.soshni...@gmail.com wrote: Good write up, although fresh vs singleton topic doesn't make sense, and doesn't reflect the spec. I responded on the gist. Dmitry On Sat, Mar 28, 2015 at 4:41 AM, Axel Rauschmayer a...@rauschma.de wrote: FWIW: I have written down my understanding of the ES6 iteration protocol (shaped by discussions I had on this mailing list). https://gist.github.com/rauschma/73e5f86a595b7709f39e -- Dr. Axel Rauschmayer a...@rauschma.de rauschma.de ___ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss ___ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss ___ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
Re: The ES6 iteration protocol
On Apr 6, 2015, at 2:23 PM, Dmitry Soshnikov dmitry.soshni...@gmail.com wrote: I guess all built-in iterators return themselves for `Symbol.iterator` protocol. So they are all singletons. I described in detail where confusion/substitution of concepts happens in that analysis in the recent two comments. I don’t think “singleton” is the correct term for the concept that Axel is trying to describe. A “singleton” is normally an kind of object for which there is only a single instances. There may be many instances of, for example %ArrayIterator%, so it isn’t correct to call %ArrayIterator% a singleton What Axel is describing might be characterized as “self iterable”, it returns itself when recieving a Symbol.iterator request. Allen ___ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
Re: The ES6 iteration protocol
Axel Rauschmayer wrote: There are two different aspects: 1. If you get an iterable, it sometimes matters whether iteration restarts when you ask the iterable for an iterator. Rather, if you have an object o and o[Symbol.iterator]() === o then you have an iterator. 2. Self-iterability is how iterators turn themselves into iterables so that constructs that work with iterables can be used. It also enables generators to play two roles: generator methods can implement `[Symbol.iterator]` and generator functions can implement iterable-returning functions. I'm not clear on what 2 means. Generator functions definitely return generator-iterators when called. A generator function gf does not have a gf[Symbol.iterator] property, though. In this particular case, I’m interested in #1. I probably have to come up with a better term for it. Yes, singleton is the wrong word. Perhaps you want iterator? :-P /be ___ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
Re: The ES6 iteration protocol
Exactly, that's what I tried to explain. Since in one case it considers just an iterable (an array), and in other case -- an iterator (which is by coincidence is also an iterable). But an array's iterator is an iterable as well, and also always returns itself for iterator protocol. Yeah, the self-iterable makes much more sense in this case. Dmitry On Monday, April 6, 2015, Allen Wirfs-Brock al...@wirfs-brock.com wrote: On Apr 6, 2015, at 2:23 PM, Dmitry Soshnikov dmitry.soshni...@gmail.com javascript:; wrote: I guess all built-in iterators return themselves for `Symbol.iterator` protocol. So they are all singletons. I described in detail where confusion/substitution of concepts happens in that analysis in the recent two comments. I don’t think “singleton” is the correct term for the concept that Axel is trying to describe. A “singleton” is normally an kind of object for which there is only a single instances. There may be many instances of, for example %ArrayIterator%, so it isn’t correct to call %ArrayIterator% a singleton What Axel is describing might be characterized as “self iterable”, it returns itself when recieving a Symbol.iterator request. Allen ___ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
Re: The ES6 iteration protocol
There are two different aspects: 1. If you get an iterable, it sometimes matters whether iteration restarts when you ask the iterable for an iterator. 2. Self-iterability is how iterators turn themselves into iterables so that constructs that work with iterables can be used. It also enables generators to play two roles: generator methods can implement `[Symbol.iterator]` and generator functions can implement iterable-returning functions. In this particular case, I’m interested in #1. I probably have to come up with a better term for it. On 06 Apr 2015, at 23:30, Dmitry Soshnikov dmitry.soshni...@gmail.com wrote: Exactly, that's what I tried to explain. Since in one case it considers just an iterable (an array), and in other case -- an iterator (which is by coincidence is also an iterable). But an array's iterator is an iterable as well, and also always returns itself for iterator protocol. Yeah, the self-iterable makes much more sense in this case. Dmitry On Monday, April 6, 2015, Allen Wirfs-Brock al...@wirfs-brock.com mailto:al...@wirfs-brock.com wrote: On Apr 6, 2015, at 2:23 PM, Dmitry Soshnikov dmitry.soshni...@gmail.com javascript:; wrote: I guess all built-in iterators return themselves for `Symbol.iterator` protocol. So they are all singletons. I described in detail where confusion/substitution of concepts happens in that analysis in the recent two comments. I don’t think “singleton” is the correct term for the concept that Axel is trying to describe. A “singleton” is normally an kind of object for which there is only a single instances. There may be many instances of, for example %ArrayIterator%, so it isn’t correct to call %ArrayIterator% a singleton What Axel is describing might be characterized as “self iterable”, it returns itself when recieving a Symbol.iterator request. Allen ___ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss -- Dr. Axel Rauschmayer a...@rauschma.de rauschma.de ___ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
Re: The ES6 iteration protocol
Good write up, although fresh vs singleton topic doesn't make sense, and doesn't reflect the spec. I responded on the gist. Dmitry On Sat, Mar 28, 2015 at 4:41 AM, Axel Rauschmayer a...@rauschma.de wrote: FWIW: I have written down my understanding of the ES6 iteration protocol (shaped by discussions I had on this mailing list). https://gist.github.com/rauschma/73e5f86a595b7709f39e -- Dr. Axel Rauschmayer a...@rauschma.de rauschma.de ___ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss ___ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
