For example I have multiple currencies

dollar.ex

defmodule Multicurrency.Currency.Dollar do
  @enforce_keys [:amount]
  defstruct [:amount]

  @type t :: %__MODULE__{
    amount: integer()
  }

  @spec new(number()) :: Multicurrency.Currency.Dollar.t()
  def new(amount) do
    %__MODULE__{amount: amount}
  end
end

franc.ex

defmodule Multicurrency.Currency.Franc do
  @enforce_keys [:amount]
  defstruct [:amount]

  @type t :: %__MODULE__{
    amount: integer()
  }

  @spec new(number()) :: Multicurrency.Currency.Franc.t()
  def new(amount) do
    %__MODULE__{amount: amount}
  end
end

They are basically the same and I wonder if it’s possible to have some kind of a generic struct or a protocol for structs that will define common keys and allow to pattern match on the instances of that struct:

defmodule Multicurrency.Currency do
  @enforce_keys [:amount]
  defstruct [:amount]

  @type t :: %__MODULE__{
    amount: integer()
  }

end

defmodule Multicurrency.Currency.Franc do
  @impl Multicurrency.Currency

  @spec new(number()) :: Multicurrency.Currency.t()
  def new(amount) do
    %__MODULE__{amount: amount}
  end
end

def equals?(Multicurrency.Currency{amount: a1},  Multicurrency.Currency{amount: a2}) do
    a1 == a2
  end

Does it even make sense?