atom(X) succeeds if X currently stands for an atom.
Examples
?- atom(abc).
yes
?- atom(1).
no
?- atom(X).
no
?- atom(_).
no
?- atom(a(b,c)).
no
?- atom([a,b,c]).
noatom(X) - checks that a term is an atom.atom(X) succeeds if X currently stands for an atom.
?- atom(abc).
yes
?- atom(1).
no
?- atom(X).
no
?- atom(_).
no
?- atom(a(b,c)).
no
?- atom([a,b,c]).
no