currently on the prolog side you have to convert a normal list like \[1, 2, 3\] to a float_array with the help of some helper predicates in helper.pl.
When inputing or recieving a vector you just get a normal Prolog List.
Internaly that List gets converted to an float_array from the SICStus struct module to be then able to convert it into a c++ array, with the c Interface.