NDLI: Polymorphic queries across sets, bags, and lists

Content Provider	ACM Digital Library
Author	Wong, Limsoon
Abstract	Bulk data types such as sets, bags, and lists are an important component of a modern query language. It is desirable that operations on one bulk data type (such as sets) that have analogous counterparts in other bulk data types (such as bags and list) be expressed using the same expression. This kind of uniformity is achieved only to a limited degree in object-oriented languages, as these languages have the type information loss problem. Languages based on parametric polymorphism achieve this uniformity in a much better way, but only upto "bracket-switching." That is, in these languages, a query over bags that is analogous to a query over sets, are identical upto interchanging the set and bag brackets. This paper presents a simple extension to a popular parametric polymorphic type system. We show that it is possible to construct a query language around this type system so that the same expression can be used to implement analogous queries across sets, bags, and lists. Furthermore, this uniformity is achieved without any loss in type information.
Starting Page	39
Ending Page	44
Page Count	6
File Format	PDF
ISSN	03621340 15581160
DOI	10.1145/202176.202181
Journal	ACM SIGPLAN Notices (SIGP)
Volume Number	30
Issue Number	4
Language	English
Publisher	Association for Computing Machinery (ACM)
Publisher Date	1983-05-01
Publisher Place	New York
Access Restriction	One Nation One Subscription (ONOS)
Content Type	Text
Resource Type	Article
Subject	Computer Graphics and Computer-Aided Design Software

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