Draft Type Systems for Records Revisited

We explore the design space for type systems with poly-morphic records. We design record systems for extension , concatenation and removal of elds. Furthermore, we design a record system where eld labels become rst class values. That means, we can now quantify over eld lables and pass them around as arguments. We base our design on the HM(X) framework. HM(X) is a general framework for Hindley/Milner type systems that are pa-rameterized in the constraint domain X. HM(X) enables us to design record systems in a systematic way retaining type inference with principal types. That means, designing record systems becomes construction of constraint systems which model record systems.