Looks like a big release! I'm curious -- is anyone actually using HHVM, either in production or for personal use?
It's a good language, especially if you're one of those people who like PHP except for the few irritating things Hack fixes, it just seems like it died before it could get a good community around it.
I just don't see a reason to follow them on this journey since they decided not to be compatible with PHP back in 3.3.
Aren't Facebook using it?
If you read this blog post closely, you will notice several interesting points in the Future Changes, which hint at making Hack a significantly saner language than PHP, especially around type-soundness.
> Several behaviors will be removed from PHP arrays; the general principle is that PHP arrays should work as “vec or dict”.
> Int-like string keys will not be converted to integers.
> Binding references to array elements will not be permitted.
> The values null, false, or uninitialized variables will not be able to be treated as arrays.
> Empty strings will not be able to be treated as arrays.
> Arrays will not be able to be compared to non-arrays.
> Non-arraykey values will not be able to be used as array keys and will not be automatically coerced.
> Arrays will not be able to be used with the plus (+) operator.
This is a massive change that goes a long way towards making the most prominent, core data structure of any php codebase be sound.
Other examples of introducing type soundness:
> Undefined constants will no longer be converted to strings
> ints will wrap in future releases, instead of being converted to floats, allowing the type of int + int to be int, instead of int + int = num.
Also on a personal level I'm really not sure why anyone would want to go that direction. Of all the problems people usually say they have with PHP, just fixing the type system is not even close to #1. If Hack then really is a different language and you don't like PHP, why not migrate to something completely different?
What this demonstrates is that one can have a much safer programming language while keeping the key attributes of PHP that make it great: each web request having isolated state, concurrency model, and programmer workflow (ref. https://slack.engineering/taking-php-seriously-cf7a60065329).
Yes, I'm not necessarily advocating for any web developer to start building in Hack now -- mainly because it lacks PHP's rich ecosystem. The good folks working on the PHP language may be interested in these changes though.
For server-side web programming, what shall one adopt?
Python and Ruby are great dynamically-typed languages, with rich ecosystems, but don't have any type system. This makes maintenance, and evolution of the codebase, tricky in the long run.
For languages that do have type-systems: Go's is a bit too simplistic, while Java/Scala have robust type systems but are rather slow and don't hit the programmer workflow sweet spot.
There's no silver bullet around.
I wonder if this is related to the plans to add a pluggable architecture to Yarn 2.0 and support languages other than JavaScript.
