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Factorial Calculator - Hack Typing CST Test

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Factorial Calculator — Hack Code

Calculates factorial of a number using recursion.

<?hh
function factorial(int $n): int {
	return $n === 0 ? 1 : $n * factorial($n - 1);
}
<<__EntryPoint>>
function main(): void {
	echo factorial(5) . "\n";
}

Hack Language Guide

Hack is a programming language developed by Facebook as a dialect of PHP. It adds static typing, enhanced performance, and modern programming features while maintaining compatibility with PHP, enabling rapid development of large-scale web applications.

Primary Use Cases

  • ▸Large-scale web application development
  • ▸Maintaining and modernizing PHP codebases
  • ▸Developing scalable backend services
  • ▸Improving code safety with static typing
  • ▸Rapid iteration and prototyping in web projects

Notable Features

  • ▸Optional static typing for safety and performance
  • ▸Type inference to reduce boilerplate
  • ▸Compatibility with PHP codebases
  • ▸Collections and async support
  • ▸Generics and shape types for advanced type modeling

Origin & Creator

Developed by Facebook in 2014.

Industrial Note

Hack is mainly used for large-scale web applications, especially for projects requiring high performance, maintainability, and gradual typing within PHP-based systems.

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