ExBitset provides the functionality to create/query bitarray sets.

To define a set constructor you first need to specify all possible set elements. This is done via the defbitset macro:

defmodule Roles
  import ExBitset, only: [defbitset: 1]

  defbitset [:admin, :owner, :writer, :viewer, :guest]
end

Then, create a new set specifying all of the elements in it:

roles = ExBitset.new(Roles, [:admin, :owner])

To then query the set, you can use any of the following functions:

ExBitset.member?(roles, :owner) # => true

roles2 = ExBitset.new(Roles, [:admin, :writer])

ExBitset.union(roles, roles2) |> Enum.to_list() # => [:admin, :owner, :writer]
ExBitset.intersection(roles, roles2) |> Enum.to_list() # => [:admin]
ExBitset.subtract(role, roles2) |> Enum.to_list() # => [:owner]

# OR alternatively using Enum functions
Enum.join(roles, ", ") # => "admin, owner"
Enum.map(roles, &to_string/1) # => ["admin", "owner"]