DocumentationHSLReferenceFunctionHH\Lib\C\reduce_with_key

HH\Lib\C\reduce_with_key

Requires the Hack Standard Library to be installed.

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

Reduces the given KeyedTraversable into a single value by applying an accumulator function against an intermediate result and each key/value

namespace HH\Lib\C;

function reduce_with_key<Tk, Tv, Ta>(
  KeyedTraversable<Tk, Tv> $traversable,
  (function(Ta, Tk, Tv): Ta) $accumulator,
  Ta $initial,
): Ta;

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

Parameters

KeyedTraversable<Tk, Tv> $traversable
(function(Ta, Tk, Tv): Ta) $accumulator
Ta $initial

Returns

Ta