Is there a way to have Elixir Records without default values?

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4

Answer

  1. Is there a way to have Records not accept default values?

No. This is not possible with Records. Records were never intended for this use case and forcing this abstraction into them would only complicate things. While one could use a wrapper new method, it would still be a lot of boilerplate and all the validation for type would be on the user.

  1. At the time of this writing, there are none. However, in another post I created a macro that achieves this purpose: How to define Macro for a new Type? - #10 by Fl4m3Ph03n1x - Questions / Help - Elixir Programming Language Forum

In that post I propose an API and then I refine it with the community’s help. For those of you who are curious, it can be used like this:

type.ex

defmodule Type do
  import NewType

  deftype(Name, String.t())
end

test.ex

defmodule Test do
  alias Type.Name

  @spec print(Name.t()) :: binary
  def print(name), do: Name.extract(name)

  def run_1 do
    # dialyzer complains !
    Name.new(1)
  end

  def run_2 do
    # dialyzer complains !
    print("john")
  end

  @spec run_3 :: binary
  def run_3 do
    print(Name.new("dow"))
  end
end
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