Polymorphic Strictness Analysis Using Frontiers

Abstract

This paper shows how to implement sensible polymorphic strictness analysis using the Frontiers algorithm. A central notion is to only ever analyse each function once, at its simplest polymorphic instance. Subsequent non-base uses of functions are dealt with by generalising their simplest instance analyses. This generalisation is done using an algorithm developed by Baraki, based on embedding-closure pairs. Compared with an alternative approach of expanding the program out into a collection of monomorphic instances, this technique is hundreds of times faster for realistic programs. There are some approximations involved, but these do not seem to have a detrimental effect on the overall result. The overall effect of this technology is to considerably expand the range of programs for which the Frontiers algorithm gives useful results reasonably quickly. 1 Introduction The Frontiers algorithm was introduced in [CP85 ] as an allegedly efficient way of doing forwards strictness analysis, al..