edu.nyu | Geospatial metadata records for New York University | Dataset library

Got an answer from Andrew Reynolds on the CVC4 mailing list:

First, notice that we have updated to a new API (https://github.com/CVC4/CVC4/blob/master/src/api/cvc4cpp.h).
Coincidentally, I just submitted a PR that adds the interface for getting the required constructor you are looking for, in the new API: https://github.com/CVC4/CVC4/pull/4817

If you are interested in the old API, your code is almost correct, however, there is a subtle difference in what we expect to be cast.

In particular, in SMT-LIB casts are applied to constructor operators, not terms (you may be interested in this discussion https://github.com/Z3Prover/z3/issues/2135). This means that the AST of a casted nil term in CVC4 is: (APPLY_CONSTRUCTOR (APPLY_TYPE_ASCRIPTION None T)) not (APPLY_TYPE_ASCRIPTION (APPLY_CONSTRUCTOR None) option[Int]) Unfortunately, there is a complication in the old API about what T is. It is not "option[Int]", instead it is "the type of constructors of type option[Int]", or what we call a "constructor type".

Here is the corrected code for creating the expression: