A Verification of Extensible Record Types

In the strive for more flexible type checkers, Remy and Wand proposed flexible record types in order to avoid the complications involved with subtyping. We formalize their approach in the framework of order-sorted logic. R, the considered language of records, is so simple that the type inference algorithm can be expressed as a constraint solver in first-order logic. We specify expressions and types, give an effective method for finding a typing, and state soundness results. R can be the basis of type inference for object-oriented programming languages.