Making Bubbling Practical

TL;DR

This paper introduces a new algorithm for bubbling in functional logic computations that uses only local information, making it more practical and competitive.

Contribution

It proposes a novel local-information-based bubbling algorithm using dominator attributes, improving practicality and efficiency.

Findings

The new algorithm accesses only local information during bubbling.

Maintains dominator attributes efficiently during graph transformations.

Demonstrates theoretical competitiveness with existing methods.

Abstract

Bubbling is a run-time graph transformation studied for the execution of non-deterministic steps in functional logic computations. This transformation has been proven correct, but as currently formulated it requires information about the entire context of a step, even when the step affects only a handful of nodes. Therefore, despite some advantages, it does not appear to be competitive with approaches that require only localized information, such as backtracking and pull-tabbing. We propose a novel algorithm that executes bubbling steps accessing only local information. To this aim, we define graphs that have an additional attribute, a dominator of each node, and we maintain this attribute when a rewrite and/or bubbling step is executed. When a bubbling step is executed, the dominator is available at no cost, and only local information is accessed. Our work makes bubbling practical, and theoretically competitive, for implementing non-determinism in functional logic computations.