advent/src/advent/util.cr

class Array(T)
  def zip_with(other : Array(R), &block : T, R -> U) forall R, U
    dest = [] of U
    zip(other) do |l, r|
      dest << yield l, r
    end
    dest
  end

  def union
    reduce(T.new) do |l, r|
      l | r
    end
  end

  def intersect
    reduce do |l, r|
      l & r
    end
  end
end