Question

I have parsed a json list and it comes out with each element like:

{struct,
 [
  {<<"name">>, "<<a name>>"},
  {<<"id">>, "<<an id>>""}
 ]
}

I would like to specify this as a type, but I get an error with the following, presumably because I’m using two elements in the list definition:

-type user_data() :: {struct, [{Name_key::Binary, Name_value::Binary},{ID_key::Binary, ID_value::Binary}]}.

Is there any way to do what I’m trying to do?

Answer 1

You can do

-type user_data() :: {struct, [{Name_key::binary(), Name_value::binary()}|{ID_key::binary(), ID_value::binary()}]}.

meaning a list every element of which is either a {Name_key::binary(), Name_value::binary()} or an {ID_key::binary(), ID_value::binary()}. This isn’t quite what you want but may be good enough.