syntax, and syntactic and semantic domains of a flow graph Figure 9. Semantic equations Def and Exp of a flow graph The first argument to the functions Def and Exp specifies a set of nodes that represent a flow graph, from which the element(s) of current interest are selected by pattern matching.

The aim of the FAST Project is to provide an implementation of a functional language, Haskell, on a transputer array. An important component of the system is a highly optimising compiler for Haskell to a single transputer. This paper presents a methodology for describing the optimisations and code generation for such a compiler, which allows the exploitation of many standard and some new techniques in a clear and concise notation. Results are included showing that the optimisations give significant improvement over the standard combinator and (Johnsson's 1984) G-machine implementations. 1 Introduction The FAST (Functional programming for ArrayS of Transputers) Project, funded by the UK government, is a collaboration between the University of Southampton, Imperial College, London and Meiko Ltd. of Bristol. The aim is to provide an implementation of a pure, lazy, functional language such as Haskell [12] on transputer arrays. The methodology for distribution is a variant of the process ...

Implementations of lazy functional languages have not as yet approached the speed of execution provided by imperative, or even non-lazy functional languages. It has been suggested that the answer to this problem lies with powerful analyses, based on abstract interpretation, such as strictness analyses that can deal with arbitrary data structures and higher-order functions. In this paper we present a break down of the benefits of a number of analyses, each performed at increasing levels of sophistication, and analysed for a set of medium-sized functional programs. We conclude that the benefits of important analyses are limited. 1 Introduction The FAST (Functional programming on ArrayS of Transputers) project team at Southampton have developed an optimising compiler for a lazy functional language to a single processor. In this paper we report on measurements that illustrate the run time effects of the compile time analysis performed. Strictness analysis and boxing analysis are the most ...

The aim of the FAST project is to provide an implementation of a lazy functional language on a transputer array. An important component of this system is a highly optimising compiler and runtime system for a single transputer. Efficient storage management is crucial in such an implementation, and this paper explores the demands placed on the storage manager by our compiled code. Statistics are presented illustrating the lifetime characteristics of cells, a break down of claimed cells by type, and other information which is of interest to the designer of a storage management system. We conclude that most cells are short lived, and that cell turnover is quite high. In addition, application cells are found to die much younger than cells of other types. We also examine the effect of vector apply cells on suspension forming activities. Finally we explore the possibility of using contextual information when predicting the lifetime of application and vector application cells, and suggest ways...

The performance of program-derived combinator graph reduction is known to be superior to that of graph reduction based on a fixed set of standard combinator. The major advantage of program-derived combinator reduction is that it uses less transient store than standard combinator reduction. We show on what activities a combinator reduction algorithm spends its execution time. Based on this analysis we show that it depends to a large extent on the application how much faster a program will run if programderived combinator are used instead of standard combinator. The analysis is based on experimental evidence obtained from a small bench-mark of medium-size functional programs. Performance gains of up to 11 × are reported for target architectures on which each memory reference consumes one unit of time. The results are valid for implementations of combinator graph reduction that use binary graphs. KEY WORDS Turner’s combinator G-machine Performance modelling Graph reduction Instruction level timing Small functional bench-mark

Mere academic toys or the tools of the future? Lazy functional programming languages have undoubted attractive properties. This thesis explores their potential, from the programmer's point of view, for implementing interactive and graphical applications to which they do not seem immediately suited. The discussion is centred round two example applications. One is a graphical design program based on an idea of the artist M. C. Escher. The thesis argues that the graphical user interface may be encapsulated in an "interpret " function that when applied by a mouse click to an interface of appropriate type yields the required behaviour. The second example is a monitoring interpreter for a functional language. The idea is that if the mechanics of the reduction are presented at a suitable level of abstraction, this may be used to give insight into what is going on. On the basis of this the programmer might modify the code so that a program runs more efficiently in terms of speed and memory requirements. Problems of displaying the reduction are addressed, and solutions proposed for overcoming these: displaying the graph as a spanning tree, to ensure planarity, with extra leaves