-module(union_adt). -export([new/1, new_a/1, new_rec/1]). -record(rec, {x = 42 :: integer()}). -opaque u() :: 'aaa' | 'bbb' | #rec{}. new(a) -> aaa; new(b) -> bbb; new(X) when is_integer(X) -> #rec{x = X}. %% the following two functions (and their uses in union_use.erl) test %% that the return type is the opaque one and not just a subtype of it new_a(a) -> aaa. new_rec(X) when is_integer(X) -> #rec{x = X}.