Abstract

Performing a depth-first search of a graph is one of the fundamental approaches for solving a variety of graph algorithms. Implementing depthfirst search efficiently in a pure functional language has only become possible with the advent of imperative functional programming. In this paper we mix the techniques of pure functional programming in the same cauldron as depth-first search to yield a more lucid approach to viewing a variety of graph algorithms. This claim will be illustrated with several examples. 1 Introduction Graph algorithms have long been a challenge to functional programmers. It has not been at all clear how to express such algorithms without using side effects to achieve efficiency. For example, many texts provide implementations of search algorithms which are quadratic in the size of the graph (see [7, 3, 2], for instance), compared with the standard linear implementations given for imperative languages (see [1], for instance). In this paper we implement a variety of ...

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