[RFC] Improve core types for (Async) Iterable/Iterator/Generator #3990
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leebyron
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* Changes `@@iterator` method to return more specific type in Generators. * An `$Iterator` is an `$Iterable` * Add optional `return` and `throw` methods to `$Iterator` (http://www.ecma-international.org/ecma-262/7.0/#table-54) * A `$Generator` is an `$Iterator` * Fix mistaken function name to `$asyncIterate` to match style of `$iterate`.
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nmote
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Library definitions
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@nmote do you think this is ok to merge? |
| @@iterator(): $Iterator<Yield,Return,Next>; | ||
| next(value?: Next): IteratorResult<Yield,Return>; | ||
| +return?: <R>(value: R) => IteratorResult<Yield,R|Return>; |
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A return definition would be great. :)
I'd think it should just be () => IteratorResult<Yield, Return> (same for $AsyncIterator below) as long as that doesn't break passing a generator where an iterator is expected.
If you're hand-writing a return method to handle abrupt completions, you normally wouldn't accept any value because none are passed on IteratorClose. See http://www.ecma-international.org/ecma-262/7.0/#sec-iteratorclose
| interface $Iterable<+Yield,+Return,-Next> { | ||
| @@iterator(): $Iterator<Yield,Return,Next>; | ||
| } | ||
| type Iterable<+T> = $Iterable<T,void,void>; | ||
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| interface Generator<+Yield,+Return,-Next> { | ||
| interface $Iterator<+Yield,+Return,-Next> extends $Iterable<Yield,Return,Next> { | ||
| @@iterator(): $Iterator<Yield,Return,Next>; |
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I wish Flow didn't require an @@iterator method on Iterators, even though they typically have one that returns this by convention. (But I'm not sure how to use this without hacks in any case: #1163.)
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#6075 has some relevant discussion
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@nmote anything preventing merging this? |
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Happy comment anniversary @goodmind! I'm also finding lots of issues with async generators, but don't have the OCaml chops to help here. |
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TIL that there's a convention for
The TS type for |
@@iteratormethod to return more specific type in Generators.$Iteratoris an$Iterablereturnandthrowmethods to$Iterator(http://www.ecma-international.org/ecma-262/7.0/#table-54)$Generatoris an$Iterator$asyncIterateto match style of$iterate.