Example:
static PlAtom ATOM_read("read");
PREDICATE(test, 1)
{ if ( A1 == ATOM_read )
...;
}
This case raises a type_error if A1 is not an
atom. Otherwise it extacts the atom-handle and compares it to the
atom-handle of the global PlAtom object. This approach is
faster and provides more strict type-checking.