HH\Lib\C\firstx
Returns the first element of the given Traversable, or throws if the Traversable is empty
namespace HH\Lib\C;
function firstx<T>(
Traversable<T> $traversable,
): T;
- For possibly empty Traversables, see
C\first. - For possibly null Traversables, see
C\nfirst. - For single-element Traversables, see
C\onlyx. - For Awaitables that yield Traversables, see
C\firstx_async.
Time complexity: O(1) Space complexity: O(1)
Parameters
Traversable<T>$traversable
Returns
T
Examples
$strings = vec["a", "b", "c"];
$first_string = C\firstx($strings);
echo "First string in traversable: $first_string \n";
//Output: First string in traversable: a
$empty_traversable = vec[];
$first_element = C\firstx($empty_traversable);
//Output: Hit a php exception : exception 'InvariantViolationException' with message
//'HH\Lib\C\firstx: Expected at least one element.'