Bounded quantification allows quantified types to specify subtyping bounds for the type variables they introduce. It has undecidable subtyping and type checking. This paper shows that subclassing-bounded quantification---type variables have subclassing bounds---has decidable type checking. The main difficulty is that, type variables can have either upper bounds or lower bounds, which complicates the minimal type property.
In ACM Workshop on Types in Language Design and Implementation (TLDI 05)
Publisher Association for Computing Machinery, Inc.
Copyright © 2007 by the Association for Computing Machinery, Inc. Permission to make digital or hard copies of part or all of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. Copyrights for components of this work owned by others than ACM must be honored. Abstracting with credit is permitted. To copy otherwise, to republish, to post on servers, or to redistribute to lists, requires prior specific permission and/or a fee. Request permissions from Publications Dept, ACM Inc., fax +1 (212) 869-0481, or email@example.com. The definitive version of this paper can be found at ACM’s Digital Library --http://www.acm.org/dl/.