| public static of ( $value, Widmogrod\FantasyLand\Monoid $side = null ) | ||
| $side | Widmogrod\FantasyLand\Monoid | |
public function provideData()
{
$addOne = function ($x) {
return Writer::of($x + 1);
};
$addTwo = function ($x) {
return Writer::of($x + 2);
};
return ['writer 0' => ['$f' => $addOne, '$g' => $addTwo, '$x' => 10]];
}
public function test_it_should_filter_with_logs()
{
$data = [1, 10, 15, 20, 25];
$filter = function ($i) {
if ($i % 2 == 1) {
return W::of(false, S::of("Reject odd number {$i}.\n"));
} elseif ($i > 15) {
return W::of(false, S::of("Reject {$i} because it is bigger than 15\n"));
}
return W::of(true);
};
list($result, $log) = f\filterM($filter, $data)->runWriter();
$this->assertEquals([10], $result);
$this->assertEquals('Reject odd number 1.
Reject odd number 15.
Reject 20 because it is bigger than 15
Reject odd number 25.
', $log->extract());
}
/**
* log :: Writer s w => w -> m a
*
* Add a log to the writer without modifying the value
*
* @param FantasyLand\Monoid $log
*
* @return callable
*/
function log(FantasyLand\Monoid $log)
{
return function ($value) use($log) {
return M\Writer::of($value, $log);
};
}
