Features
- User definable subtyping relation
- Support of type qualifiers
- XDuce like type system for XML documents
- Subtyping of function types
Type systems built directly into the compiler or interpreter of a programming language cannot be easily extended to keep track of run-time invariants of new abstractions. Yet, programming with domain specific abstractions could benefit from additional static checking. XTL library aims at extending type system of C++ to support domain specific abstractions. The main contribution is a programmable ``subtype'' relation.