HH\Lib\C\find_key

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

Description

namespace HH\Lib\C;

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

Parameters