TYPE CLASSES IN HASKELL

This article defines a set of type inference rules for resolving overl oading introduced by type classes, as used in the functional programmi ng language Haskell. Programs including type classes are transformed i nto ones which may be typed by standard Hindley-Milner inference rules . In contrast to other work on type classes, the rules presented here relate directly to Haskell programs. An innovative aspect of this work is the use of second-order lambda calculus to record type information in the transformed program.