HH\Lib\Vec\diff_by

This API is part of the Hack Standard Library, not HHVM itself.
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This function is available as Vec\diff_by() in Facebook's www repository.

Returns a new vec containing only the elements of the first Traversable that do not appear in the second one, where an element's identity is determined by the scalar function

Description

namespace HH\Lib\Vec;

function diff_by<Tv, Ts as arraykey>(
  Traversable<Tv> $first,
  Traversable<Tv> $second,
  (function(Tv):Ts) $scalar_func,
): vec<Tv>;

For vecs that contain arraykey elements, see Vec\diff().

Parameters