Comment by SabrinaJewson

In type theory, all singleton types are isomorphic and have no useful distinguishing characteristics (indeed, this is true of all types of the same cardinality – and even then, comparing cardinalities is always undecidable and thus irrelevant at runtime). So your Nine type doesn’t really make sense, because you may as well just write Unit. In general, there is no amount of introspection into the “internal structure” of a type offered; even though parametricity does not hold in general (unless you postulate anticlassical axioms), all your functions that can run at runtime are required to be parametric.