SWI-Prolog -- atom

Availability:built-in

atom_string(?Atom, ?String)

Bi-directional conversion between an atom and a string. At least one of the two arguments must be instantiated. An initially uninstantiated variable on the “string side'' is always instantiated to a string. An initially uninstantiated variable on the “atom side'' is always instantiated to an atom. If both arguments are instantiated, their list-of-character representations must match, but the types are not enforced. The following all succeed:

atom_string("x",'x').
atom_string('x',"x").
atom_string(3.1415,3.1415).
atom_string('3r2',3r2).
atom_string(3r2,'3r2').
atom_string(6r4,3r2).