private function ifMatch(callable $matcher, callable $predicate, callable $action) : Optional
{
return $this->bindMonad(sequence(conditionally(curry($matcher, 2)($predicate), $action), optional));
}
/**
* Invoke a value if it is callable.
*
* @param array $args optional array of arguments to pass to the optional callable
* @return Chain the result of the invocation wrapped into a Chain, or empty Chain
*/
public function invokeArray(array $args = []) : Chain
{
return $this->continue(conditionally(is_callable, curry(reverse(call_user_func_array), 2)($args)));
}
/**
* Filter a value of the monad by a predicate.
*
* If the value matches the predicate, this monad will be returned,
* otherwise monad with NULL value will be returned.
*
* @param callable $predicate the predicate to test the value
* @return Optional this monad if the value matches the predicate,
* otherwise a monad with NULL value
*/
public function filter(callable $predicate) : Optional
{
return $this->bind(conditionally($predicate, pass_through));
}
