Context-sensitive rewriting is a simple restriction of rewriting which is formalized by imposing fixed restrictions on replacements. Such a restriction is given on a purely syntactic basis: it is (explicitly or automatically) specified on the arguments of symbols of the signature and inductively extended to arbitrary positions of terms built from those symbols. Termination is not only preserved but usually improved and several methods have been developed to formally prove it. In this paper, we investigate the definition, properties, and use of context-sensitive rewriting strategies, i.e., particular, fixed sequences of context-sensitive rewriting steps. We study how to define them in order to obtain efficient computations and to ensure that context-sensitive computations terminate whenever possible. We give conditions enabling the use of these strategies for root-normalization, normalization, and infinitary normalization. We show that this theory is suitable for formalizing ...

Six implementations of different lazy functional languages are compared using a common benchmark of a dozen medium-sized programs. The experiments that were carried out two years ago have been repeated to chart progress in the development of these compilers. The results have been extended to include all three major Haskell compilers. Over the last two years, the Glasgow Haskell compiler has been improved considerably. The other compilers have also been improved, but to a lesser extent. The Yale Haskell compiler is slower than the Glasgow and Chalmers Haskell compilers. The compilation speed of the Clean compiler is still unrivalled. Another extension is a comparison of results on different architectures so as to look at architectural influences on the benchmarking procedure. A high-end architecture should be avoided for benchmarking activities, as its behaviour is uneven. It is better to use a midrange machine if possible. 1 Introduction In the previous benchmark paper [10], which wi...

The FAST compiler is a backend for compilers of lazy functional languages. There are two versions of the compiler: one that takes a rather simple lazy functional language as input and a second that accepts a language similar to Miranda. On output the compiler produces a set of macro calls that are normally turned into a C program by one of the code generators that have been developed for FAST. Such a C program must be compiled by a C compiler and linked with the appropriate runtime library to form an executable. This document decsribes how to use the FAST compiler. Familiarity with functional languages and their implementation methods is required to make full use of this document. 1 Introduction The FAST (Functional programming on ArrayS of Transputers) project team at Southampton has developed an optimising compiler for a lazy functional language on a single processor [6]. This document describes how to use the compiler. The compiler accepts on input a language called Intermediate th...

A clustered architecture has been designed to exploit divide and conquer parallelism in functional programs. The programming methodology developed for the machine is based on explicit annotations and program transformations. It has been successfully applied to a number of algorithms resulting in a benchmark of small and medium size parallel functional programs. Sophisticated compilation techniques are used such as strictness analysis on non-flat domains and RISC and VLIW code generation. Parallel jobs are distributed by an efficient hierarchical scheduler. A special processor for graph reduction has been designed as a basic building block for the machine. A prototype of a single cluster machine has been constructed with stock hardware. This paper describes the experience with the project and its current state. 1 Introduction Functional programming is founded on the lambda calculus, which is a mathematical theory that provides a sound basis for work on reduction machines [5]. This is p...

We formalize the notion of syntactic replacement restriction, which is useful for modeling reduction-based systems which compute with terms and impose restrictions on the possible computations (typically by means of strategies). We emphasize the syntactic flavour of our approach: the restrictions are associated to components of terms and (in principle) they do not depend on either a particular Term Rewriting System or a computational mechanism (like rewriting, narrowing, residuation, etc.). The replacement restrictions can be used to improve the computational behavior of the unrestricted mechanism. We give a general descriptive and algebraic framework to deal with replacement restrictions. For the descriptive part, we introduce and motivate properties which characterize classes of replacement restrictions. For the algebraic side, the set of replacement restrictions is presented as a complete Boolean algebra. The algebraic operations (and others which we also define) can be used to com...