HH\Lib\C\find_key

Requires the Hack Standard Library to be installed.

Facebook Engineer?

This function is available as C\find_key() in Facebook's www repository.

Returns the key of the first value of the given KeyedTraversable for which the predicate returns true, or null if no such value is found

namespace HH\Lib\C;

function find_key<Tk, Tv>(
  KeyedTraversable<Tk, Tv> $traversable,
  (function(Tv): bool) $value_predicate,
): ?Tk;

Time complexity: O(n) Space complexity: O(1)

Parameters