Background

I am a fan of dialyzer and friends (looking at Gradient) and I try to have sepcs in my code as much as I can. To this end, I am playing with guards and I want my guard definitions to also have a typespec:

defmodule AuctionHouse.Shared.ExtraGuards do
  @moduledoc """
  Contains additional guards to use in functions.
  """

  defguard is_pos_integer(value) when is_integer(value) and value > 0
end

Problem

So, now that I have this simple guard, I want a spec for it. However, dyalizer’s suggestion doesn’t strike me as exactly human readable.

@spec is_pos_integer(any) ::
          {:__block__ | {:., [], [:andalso | :erlang, ...]}, [],
           [{:= | {any, any, any}, list, [...]}, ...]}
defguard is_pos_integer(value) when is_integer(value) and value > 0

I believe this is likely defined as a function that takes any as an argument but the return type is very difficult for me to understand. I assume it means it creates erlang code, like a macro, but I can’t make sense of it.

Questions

• What does the return type mean?
• Is there a way to make this more human readable? If so, how?