Needed Computations Shortcutting Needed Steps

Abstract

We define a compilation scheme for a constructor-based, strongly-sequential, graph rewriting system which shortcuts some needed steps. The object code is another constructor-based graph rewriting system. This system is normalizing for the original system when using an innermost strategy. Consequently, the object code can be easily implemented by eager functions in a variety of programming languages. We modify this object code in a way that avoids total or partial construction of the contracta of some needed steps of a computation. When computing normal forms in this way, both memory consumption and execution time are reduced compared to ordinary rewriting computations in the original system.

A New Functional-Logic Compiler for Curry: Sprite

“…We note that Sprite currently does not perform optimizations such as deforestation [14] or unboxing [21]. These, and other optimizations of ICurry, e.g., [6], could potentially impact the benchmark results. Inspecting the output of GHC reveals that the tak program (incidentally, the worse-case for Sprite) is optimized by GHC to a fullyunboxed computation.…”

“…We take these results as an indication that the functional parts of Sprite -i.e., those parts responsible for pattern-matching, rewriting, memory management, and optimization -although not as finely-tuned as their GHC counterparts, still compare favorably to most mainstream Curry compilers.We note that Sprite currently does not perform optimizations such as deforestation[14] or unboxing[21]. These, and other optimizations of ICurry, e.g.,[6], could potentially impact the benchmark results. Inspecting the output of GHC reveals that the tak program (incidentally, the worse-case for Sprite) is optimized by GHC to a fullyunboxed computation.…”