Feature request: add psalm type declarations (and push type inference)

[Ocramius]

Not sure if you are interested in this, but it is an interesting exercise, and good added value for downstream consumers.

Given (for example) combinator A:

$next = function (string $input) : int {
    return strlen($input); // simplistic example, ignore the fact that it is redundant
};

$a = new A($next, 'foo');

$a(); // int - can be inferred, in theory

This can be achieved via something like:

/**
 * @psalm-template XType
 * @psalm-template ResultType
 */
final class A extends Combinator
{
    /**
     * @psalm-param callable(XType) : ResultType $f
     * @psalm-param XType $x
     */
    public function __construct(callable $f, $x)
    {
        // ...
    }

    /** @psalm-return ResultType */
    public function __invoke()
    {
        // ...
    }

    /** @psalm-return callable() : ResultType */
    public static function closure(): callable
    {
        return static function (callable $f, $x) {
            return (new self($f, $x))();
        };
    }
}

This is currently tested in (for example) phpunit via some static analysis scripts: https://github.com/sebastianbergmann/phpunit/tree/619868463e06e5072c6e42dbae174d99cdd10fc2/tests/static-analysis

[drupol]

Hi Marco,

I will give it a try asap :-)

Thanks !!!

[drupol]

Here's a first try: https://psalm.dev/r/a71e6f340c

I don't think that it is possible to infer the type yet...

[Ocramius]

If you ignore the analysis on the internals, it's working on the inferred types (https://psalm.dev/r/0d396e5142). Specifically:

$v = new A(function (string $p) : array { return explode(',', $p); }, 'yadda');

echo $v(); // ERROR: InvalidArgument - 66:6 - Argument 1 of echo expects string, non-empty-list<string> provided

[drupol]

I just created a PR, it would be nice if you could give a quick review !

[drupol]

Thanks @Ocramius and @dannywillems for their help!

Tag 1.1.0 is available and this issue can now be closed.