library(clfpd) has the following new features, but see also below
for bugs fixed in library(fdbg):
keysorting/[2,3], analogous to Prolog’s keysort/2, is new.
scalar_product/5 takes a new option stating that some of the variables must belong to
a given set of integers.
element/3 with a ground second argument and binary
table/[2,3] have been re-implemented and run faster.