Syntax

[mnieper]

In the async generator examples, a syntax like

await yield f()

is used. However, this does not seem to be parseable by the ES6 grammar and https://github.com/lukehoban/ecmascript-asyncawait. await expects an UnaryExpression, while yield produces an AssignmentExpression.

[zenparsing]

Good point. It would have to be

await (yield f())

[mnieper]

In the implementation in Traceur, I have added a parser rule for await yield without parens. I think this grammar change should be added to this or @lukehoban's proposal because await yield will be a common idiom with async generators in place.

[zenparsing]

@mnieper What is the grammar rule you are proposing?

[mnieper]

I don't speak Ecma, but I wouldn't it suffice to say

UnaryExpression :
    ...
    await [Lexical goal InputElementRegExp] UnaryExpression
    await ... YieldExpression

?

[arv]

@mnieper Trying to clean up our parser a bit and the YieldExpression probably needs a [In] there to allow:

await yield 42 in obj

[mnieper]

Yes, this makes perfect sense.

[bterlson]

@mnieper want to file a bug here if you want this syntax in the async functions proposal?