-A:jref)A will be a JPL reference to a new Java array, whose base
type is the most specific Java type of which each member of Datums
is (directly or indirectly) an instance.
:- use_module(library(jpl)).(can be autoloaded)
NB this fails silently if
- Datums is an empty list (no base type can be inferred)
- Datums contains both a primitive value and an object
(including array) reference (no common supertype)