This API is part of the Hack Standard Library, not HHVM itself.

Returns the first element of the given Traversable, or null if the Traversable is null or empty

namespace HH\Lib\C;

function nfirst<T>(
  ?Traversable<T> $traversable,
): ?T;
  • For non-null Traversables, see C\first.
  • For non-empty Traversables, see C\firstx.
  • For single-element Traversables, see C\onlyx.


  • ?Traversable<T> $traversable