A simple implementation technique for priority search queues

Abstract

This paper presents a new implementation technique for priority search queues. This abstract data type is an amazing blend of finite maps and priority queues. Our implementation supports logarithmic access to a binding with a given key and constant access to a binding with the minimum value. Priority search queues can be used, for instance, to give a simple, purely functional implementation of Dijkstra's single-source shortest-paths algorithm. A non-technical concern of the paper is to foster abstract data types and views. Priority search queues have been largely ignored by the functional programming community and we believe that they deserve to be known better. Views prove their worth both in defining a convenient interface to the abstract data type and in providing a readable implementation.