Ideas for DEFTYPE definitions
- They should be kept in a global database, such as a hash table instead of using system properties
- They can be optimized for constant outputs reusing the same closure
- The compiler should override the database with a "local" one that wipes out all compile-time side effects (ideally this should also be the case for CLOS)
- All DEFTYPE definitions could be packed into a single file instead of multiple, scattered DEFTYPE statements, for more compact rebuilding of the database.