Programming Objects with ML-ART, an Extension to ML with Abstract and Record Types

Class-based objects can be programmed directly and efficiently in a simple extension to ML. The representation of objects, based on abstract and record types, allows all usual operations such as multiple inheritance, object returning capability, and message transmission to themselves as well as to their super classes. There is, however, no implicit coercion from objects to corresponding ones of super-classes. A simpler representation of objects without recursion on values is also described. The underlying language extends ML with recursive types, existential and universal types, and mutable extensible records. The language ML-ART is given with a call-by-value semantics for which type soundness is proved.