Using Kinds to Represent Heterogeneous Collections in a Static Type System (Extended Abstract)

We consider the problem of representing heterogeneous collections of objects in a typed polymorphic programming language in such a way that common properties of members of a collection, such as having commonly named field with a common type can be expressed in the type system. The use of such collections is widespread in object-oriented and database programming and has so far been achieved in statically typed systems only through the use of a single dynamic type, which effectively hides all the structure of a value. In this paper we exploit a system of types and kinds (sets of types) to represent dynamic values with some known properties. The type system is shown to be sound and to have a complete type inference algorithm. Comments University of Pennsylvania Department of Computer and Information Science Technical Report No. MSCIS-90-62. This technical report is available at ScholarlyCommons: http://repository.upenn.edu/cis_reports/562 Using Kinds To Represent Heterogeneous Collections In A Static Type System (Extended Abstract) MS-CIS-90-62 LOGIC & COMPUTATION 22 Peter Buneman University of Pennsylvania Atsushi Ohori University of Glasgow Department of Computer and Informat ion Science School of Engineering and Applied Science University of Pennsylvania Philadelphia, PA 19 104