Perfect hashing for strings.
atomstd/atom/atom: Vs can be compared very efficiently. If you compare only
seldomly, a straight string compare will probably be faster since
creating an atom takes some initial work.
An atom is an abstract representation of a string that can be compared quickly.
Compare if two atoms are not equal.
Compare two atoms for equality.
Create an efficient string matcher which given a list of strings returns a matching function.