$ whois hack

Hack

first released in 2014 · by Julien Verlaguet, Alok Menghrajani, Drew Paroski

$ guessprog --inspect hack

year: 2014
paradigm: multi paradigm
family: c like
memory: automatic gc
binding: gradual
safety: strong

HACK(7)

AUTHORS: Julien Verlaguet, Alok Menghrajani, Drew Paroski
HISTORY: Hack was created at Facebook and released publicly in 2014 as a dialect of PHP running on the HHVM virtual machine. Facebook's codebase was a huge amount of PHP, and Hack let engineers add static types gradually, file by file, without a rewrite. Its type checker, written in OCaml, runs as a background server that gives near-instant feedback. Hack added generics, collections, lambdas and async functions, and in 2018 HHVM dropped PHP support to focus on Hack alone.
USAGE: Hack is used mostly inside Meta, where it powers much of the web backend, plus a few other companies. Outside that circle it is a niche language with a small community.
SEE ALSO: Hack on Wikipedia ↗

$ cat shout.hack

use namespace HH\Lib\{Str, Vec};

function shout(vec<string> $words): vec<string> {
  return Vec\map($words, $w ==> Str\uppercase($w).'!');
}

<<__EntryPoint>>
function main(): void {
  $words = vec['hack', 'is', 'typed'];
  foreach (shout($words) as $word) {
    echo $word."\n";
  }
}