Abstract

This paper describes how to construct a tool that enables a programmer to view the evaluation behaviour of a lazy functional program. In the system presented, the program is first transformed so that on execution it produces a trace of expression evaluation, and this trace is passed to a browser which provides facilities for the user to navigate over the trace. We concentrate on issues around browser design, namely the identification of suitable functionality for effective navigation, and a suitable architecture for its construction. A prototype browser is presented. Keywords Lazy functional languages, debugging. 1 Introduction Over the last decade or so lazy functional languages have become increasingly popular [7, 9], with modern languages such as Miranda 1 [25] and Haskell [8] being adopted as vehicles for teaching programming and formal reasoning techniques to computer science students [23]. Despite their growing popularity, programmers can find lazy functional languages challe...

Citations