[RFC] Remove all callable type hints for consistency and performance reasons

[clue]

I'm filing this PR as an RFC to see if it makes sense to drop these type hints.

[clue]

I've seen a 5% to 10% performance improvement running any of the benchmarks from the examples/folder and have also seen some similar performance improvements in running some higher level applications (I/O intensive) with this applied.

Note that I'm not suggesting we remove all type hints. This PR merely aims to remove the callable type hint only – also for consistency reasons with the whole API. Also note that this does not contradict our efforts to eventually update to PHP 7 only (reactphp/reactphp#374), in which case we will likely reconsider adding consistent type hints for all relevant APIs.

[WyriHaximus]

That is a nice and welcome performance improvement, LGTM

[jsor]

mixed $feelings, but 😉

[morrisonlevi]

... what? I'm not a react-php user so definitely feel free to ignore me but... what does "consistency" even mean here? I would also hope any loss of type-safety for performance reasons would also be backed by reproducible numbers; is there some missing context from this PR?

Edit: A bit of background: I've altered the engine to no-op the type-checking in the past. This did not register a significant improvement gain; this is why I do not trust the claim. Again, I'm not using this project so take my complaint with that in mind.

[kelunik]

I can't reproduce any improvements in examples/94-benchmark-timers-delay.php either. Which benchmark specifically did you run and which numbers did you get?