Availability:built-in
[ISO]copy_term(+In,
-Out)Create a version if In with renamed (fresh) variables and
unify it to Out. Attributed variables (see section
6.1) have their attributed copied. The implementation of copy_term/2
can deal with infinite trees (cyclic terms). As pure Prolog cannot
distinguish a ground term from another ground term with exactly the same
structure, ground sub-terms are shared between In
and Out. Sharing ground terms does affect setarg/3.
SWI-Prolog provides
duplicate_term/2
to create a true copy of a term.