You can use a "subtype predicate" for this: https://learn.adacore.com/courses/Ada_For_The_CPP_Java_Devel...

Might be less efficient, no? At least in CL (https://www.lispworks.com/documentation/HyperSpec/Body/t_sat...) this is the case, that static type analysis isn't clever enough to work with predicate based types.