README

A proof-of-concept Hack to PHP transpiler, written in PHP

This project uses HHVM's builtin parser (hh_parse) and an existing library to turn Hack code into PHP code. It generates PHP-Parser-equivalent nodes for the original Hack AST, then prints the result.

It aims to preserve all of Hack’s types so that the resultant PHP code can be checked by a tool like Psalm, converting any asynchronous code to its synchronous equivalent.

You can install via composer (composer require --dev hacktophp/hacktophp) and run it like so:

vendor/bin/hacktophp --input=<input-file-or-folder> --output=<output-file-or-folder>

Indefinitely unsupported features

While a lot of code has easy-to-compute PHP equivalents, some builtin Hack constructs are essentially impossible to replicate:

async/await

All async/await calls have been made synchronous, converted to promises that use amphp

keyset

This valid Hack code

$a = keyset[];
$a[] = "hello";
echo $a["hello"];

transpiles to the valid (but not-equivalent) PHP code

$a = [];
$a[] = "hello";
var_dump($a["hello"]);

The only valid option here would be to convert keysets to ArrayObjects, but I'm not sure if that's wise.

Currently unsupported features

Pretty much all builtins, but I'm adding things slowly, and HH\Lib\... functions are supported via hacktophp/hsl-php
XHP
Class constant types e.g.
```
class A {
  const type Foo = int;
}
```
Docblock annotations for Parameterised extends, implements and trait - dependent on Psalm support
Docblock annotations for require extends - dependent on future Psalm support
User attributes, especially <<Memoize>>
types of const (Psalm does a reasonably good job inferring them, but it should be added for completeness)
probably many more things I haven't considered

hacktophp / hacktophp

Maintainers

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