How to Generate Custom Types with Macros

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4

I think the code you are presenting in the post can be simplified greatly.
I believe the following works:

defmacro __using__(opts) do
  fields = opts[:fields]
  keys = Keyword.keys(fields)
  fields_with_struct_name = [__struct__: __CALLER__.module] ++ fields

  quote location: :keep do
    @type t :: %{unquote_splicing(fields_with_struct)}
    defstruct unquote(keys)
  end
end