<?php

namespace TMciver\Functional\Typeclass;

/**

* An abstract class implementing the Applicative interface containing an

* implementation of the `__invoke()` magic method for convenience. Any custom

* Applicative instance you may write should extend this class.

*/

abstract class BaseApplicative implements Applicative {

function __invoke() {

// $ff, ...$fas

$args = func_get_args();

// make sure we were given at least one argument.

if (count($args) < 1) {

throw new \Exception('Must call Applicative::__invoke() with at least one argument.');

}

// Get Applicative function.

$ff = $args[0];

// Get the Applicative arguments.

array_shift($args);

$fas = $args;

$numArgs = count($fas);

if ($numArgs > 0) {

$callback = function ($applicativeFun, $applicativeArg) {

return $applicativeFun->apply($applicativeArg);

};

$result = array_reduce($fas, $callback, $ff);

} else {

$result = $this->apply($ff);

}

return $result;

}

}