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sort_by_key

Note

This is a point-in-time snapshot of the API documentation from January 2026. Going forward, we will not be maintaining a public copy of these references, and recommend users to refer to the built-in signature helpers available in the Hack LSP instead for complete and up-to-date information.

Returns a new dict sorted by the keys of the given KeyedTraversable

namespace HH\Lib\Dict;

function sort_by_key<Tk as arraykey, Tv>(
  KeyedTraversable<Tk, Tv> $traversable,
  ?(function(Tk, Tk): num) $key_comparator = NULL,
): dict<Tk, Tv>;

If the optional comparator function isn't provided, the keys will be sorted in ascending order.

  • To sort by the values of the KeyedTraversable, see Dict\sort().
  • To sort by some computable property of each value, see Dict\sort_by().

Time complexity: O((n log n) * c), where c is the complexity of the comparator function (which is O(1) if not provided explicitly) Space complexity: O(n)

Parameters​

Returns​

  • dict<Tk, Tv>