> On Feb 3, 2017, at 11:53 AM, Levi Morrison <[email protected]> wrote:
>
> One more thing: I'd like to re-emphasize that the syntax that
> JavaScript uses and the one that HHVM/Hack uses are ambiguous in the
> current class of our grammar. The following will not work unless we
> move to a more powerful grammar and parser class:
>
> (params) => expr
> (params) ==> expr
>
> This is why an un-ambiguous prefix is necessary: the prefix breaks the
> ambiguities. The syntax I have suggested in the RFC and the one I
> suggested just now are not ambiguous because distinct prefixes:
>
> fn(params) => expr
> |params| => expr
>
> I look forward to more discussion!
>
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I personally prefer the `|params| => expr` syntax.
I like the visual separation the syntax provides between auto-capturing, short
closures and regular closures. It gives the impression that it should behave
differently, rather than just being a shorter way of declaring a closure.
Below are a couple of real-world single line closures using the proposed syntax:
[1] Loop::defer(|| => ($this->when)($exception, $value));
[2] $this->watcher = Loop::delay($time, || => $this->resolve($value));
IMHO, the reduced boilerplate required makes it easier to discern what is
happening.
Regards, Aaron Piotrowski
[1] https://github.com/amphp/amp/blob/master/lib/Coroutine.php#L45-L47
[2] https://github.com/amphp/amp/blob/master/lib/Pause.php#L21-L23
