I can't speak with authority about ATD, but the following might be helpful:
Aside from algebraic data types, the big selling point of Typical is asymmetric fields. That's the crucial feature that distinguishes Typical from every other framework. Without asymmetric fields, there is no safe way to introduce or retire required fields. People using other frameworks fear required fields (rightly so), whereas Typical gives you the tools to embrace them.
Aside from algebraic data types, the big selling point of Typical is asymmetric fields. That's the crucial feature that distinguishes Typical from every other framework. Without asymmetric fields, there is no safe way to introduce or retire required fields. People using other frameworks fear required fields (rightly so), whereas Typical gives you the tools to embrace them.