Abstract

The future annotations of MultiLisp provide a simple method for taming the implicit parallelism of functional programs. Past research concerning futures has focused on implementation issues. In this paper, we present a series of operational semantics for an idealized functional language with futures with varying degrees of intensionality. We develop a set-based analysis algorithm from the most intensional semantics, and use that algorithm to perform touch optimization on programs. Experiments with the Gambit compiler indicates that this optimization substantially reduces program execution times. 1 Implicit Parallelism via Annotations Programs in functional languages offer numerous opportunities for executing program components in parallel. In a call-by-value language, for example, the evaluation of every function application could spawn a parallel thread for each sub-expression. However, if such a strategy were applied indiscriminately, the execution of a program would generate far t...

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