/**
* Maps over a Seq who's $hof function returns a FoldableInterface or array and flattens the result
* into a single sequence.
* @param callable $hof ($value, $key, $this) -> FoldableInterface|SplFixedArray|ArrayObject|ArrayIterator|array
* @return Seq
*/
public function flatMap(callable $hof)
{
$output = [];
foreach (I($this->hash) as $key => $value) {
$intermediate = call_user_func($hof, $value, $key, $this);
$array = __PRIVATE__::getArrayFrom($intermediate);
$output[] = $array !== null ? $array : __CONTRACT__::returnIsA(FoldableInterface::class, $intermediate);
}
return static::from(call_user_func_array('array_merge', $output));
}
/**
* @covers ::returnIsA
*/
public function test_returnIsA_exception()
{
$this->expectException(invalidReturn::class);
contract::returnIsA(\stdClass::class, function () {
});
}
