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...

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Two parallel implementations of a state-of-the-art ocean model are described and analyzed: one is written in the implicitly parallel language Id for the Monsoon multithreaded dataflow architecture, and the other in data parallel CM Fortran for the CM-5. The multithreaded programming model is inherently more expressive than the data parallel model. One goal of this study is to understand what, if any, are the performance penalties of multithreaded execution when implementing a program that is well suited for data parallel execution. To avoid technology and machine configuration issues, the two implementations are compared in terms of overhead cycles per required floating point operation. When simulating flows in complex geometries typical of ocean basins, the data parallel model only remains efficient if redundant computations are performed over land. The generality of the Id programming model allows one to easily and transparently implement a parallel code that computes only in the oce...