Mathematica: Webel ADT pseudo classes: 'Q: Do I have to use these EX$Val scalar "atom" thingies and the EX$Row, EX$RowList, and EX$RowMap? Can't I just use Wolfram Language Lists and Associations?' A: Of course you can also use the basic Wolfram Language!
Mathematica: Webel ADT pseudo classes: An EX$Val has concise methods for testing the type of its wrapped '$$' value: isR, isI, isB, isQ, isS. These may be used in ADT "constructor" type tests.
Mathematica: Webel ADT pseudo classes: The validity of the type of a wrapped '$$' value of an EX$Val may be checked in ADT "constructors" which have type checking utility support. This strategy has been chosen over sub-types of EX$Val.
