This paper proposes a new functional programming language called Sac (Single Assignment C) which tries to combine the best of two worlds: the efficiency and portability of C (or Fortran) and the concurrency deducable from the functional paradigm. The major objectives in the design of Sac comprise support for high performance concurrent scientific applications (number crunching), a module concept which allows for the integration of non-funtional components, and a syntax as close as possible to C. 1 Introduction Functional programming languages did not yet find a broad acceptance by application programmers outside the functional community. The reasons for this situation are manifold and differ depending on the field of application. Of primary interest in this paper are scientific applications involving complex manipulations of arrays. For this class of applications the following criteria are the most important ones for the choice of a suitable language: ffl availability of primitive a...

. This paper discusses some of the pros and cons of extending a simple functional language called Sac (for Single Assignment C) by array operations similar to those that are available in Apl. The array operations in Sac are based on the /-calculus, an algebra of arrays which provides a formalism for specifying and simplifying array operations in terms of index set manipulations. The programming techniques made possible by Sac are demonstrated by means of a functional program for the approximation of numerical solutions of partial differential equations by multigrid relaxation. This application is not only of practical relevance but also fully exposes the flavors of using high-level array operations. In contrast to specifications in other languages, e.g. in Fortran or Sisal, the Sac program is well structured, reasonably concise, and - what is most important - invariant against dimensionalities and shapes. However, sophisticated compilation techniques are necessary to avoid, whenever po...

The research presented in this thesis is about the design and implementation of Naira, a parallel, parallelising compiler for a rich, purely functional programming language. The source language of the compiler is a subset of Haskell 1.2. The front end of Naira is written entirely in the Haskell subset being compiled. Naira has been successfully parallelised and it is the largest successfully parallelised Haskell program having achieved good absolute speedups on a network of SUN workstations. Having the same basic structure as other production compilers of functional languages, Naira's parallelisation technology should carry forward to other functional language compilers. The back end of Naira is written in C and generates parallel code in the C language which is envisioned to be run on distributed-memory machines. The code generator is based on a novel compilation scheme specified using a restricted form of Milner's ß-calculus which achieves asynchronous communication. We present the f...

This paper reports on some preliminary experiments with the implementation of a concurrent version of the reduction system ß-red + on an nCUBE/2 system of up to 32 processing sites. They primarily concern basic concepts of workload partitioning and balancing, the relationship between relative performance gains and the computational complexities of the investigated programs, resource management and suitable system topologies. All programs used for these experiments realize divide and conquer algorithms and have been run with varying (sizes of) data sets and system parameters (configurations). 1 Introduction This paper reports on some preliminary experience with a very recent implementation of a concurrent version of the reduction system ß-red + [SBK92, GKK92] on an nCUBE/2 system. We favored a distributed over a shared memory system primarily for reasons of scalability, but also for the more challenging organizational problems which make it attractive from a research point of view....

The original aim of the work that led to this dissertation was to extend an existing, purely functional language with facilities for input/output and modular programming. The language is based on an untyped -calculus, i.e., program execution is defined as program transformation according to a fixed set of reduction rules including fi-reduction. Consistently, the implementation comprises an interactive reduction system which is integrated with a syntax-oriented editor: any sub-expression or program result can be submitted for (stepwise) reduction. There is no distinguished main program, no `global' environment and no explicit static part of the language -- in particular, there is no static type system. It is therefore not clear how to add one of the known solutions for input/output or modular programming to such a programming environment. Furthermore, simply adding features to the language would lead to a complex language design with weakly integrated parts, thus losing much of the appe...