A comparison of program transformation systems

Program transformation is a popular technique for attempting to improve the e ciency of a program. At a high level, program transformation is the process of taking an input program and transforming it into an improved version of the original, bearing the same constraints as the original, e.g. termination constraints. In this paper, we focus on three fold/unfold [3] based transformation systems, positive supercom- pilation [26, 25, 21, 2, 12] and distillation [8{11] and HOSC [19, 18]. We focus on derivatives of both that use labelled transition systems [12, 11] and we present these systems, their underlying theory, and implementations. Based upon these implementations we will present an analysis of how they compare to each other, and another transformation system, HOSC[19], when applied to a sample of real-world programs.