use atom_concat in gensym.pl
:- use_module(library(si)).
gensym_key(Base, BaseKey) :-
- atom_chars('gensym_', PrefixChars),
- atom_chars(Base, BaseChars),
- append(PrefixChars, BaseChars, BaseKeyChars),
- atom_chars(BaseKey, BaseKeyChars).
+ atom_concat('gensym_', Base, BaseKey).
append_id(Base, UniqueID, Unique) :-
atom_chars(Base, BaseChars),
