Evolution of partial evaluators: Removing inherited limits

Abstract

We show the evolution of partial evaluators over the past ten years from a particular perspective: the attempt to remove limits on the structure of residual programs that are inherited from structural bounds in the original programs. It will often be the case that a language allows an unbounded number or size of a particular features, but each program (being finite) will only have a finite number or size of these features. If the residual programs cannot overcome the bounds given in the original program, that can be seen as a weakness in the partial evaluator, as it potentially limits the effectiveness of residual programs. The inherited limits are best observed through specializing a self-interpreter and examining the object programs produced by specialisation of this. We show how historical developments in partial evaluators gradually remove inherited limits, and suggest how this principle can be used as a guideline for further development.