module Interned_string

Provides a functor for creating an interned string type.

An interned string is internally an int which is an index into a lookup table, which makes hashing and (non-lexicographic) comparison faster than for strings. The tradeoff is that converting an interned string to and from a string is slower, since they require table lookups instead of being no-ops.

Some notes on the implementation:

• It is not thread-safe (different applications of the functor can be used safely from different threads, but an individual interned string module is not safe to use concurrently from different threads.)
• It is leaky, meaning that an interned string, once allocated, will never be deallocated.
• Interned strings are compared based on the integer they are assigned on creation, which is not a lexicographic order, and is not necessarily stable between runs of a program.

The semantics of the other operations should be the same as for String.

We don't fix the memory leak with weak pointers for performance reasons. See jane/interns/ahuq/strint/README at revision b9a2b9dbf290.