SISAL (Streams and Iteration in a Single Assignment Language) is a general-purpose single assignment functional programming language with strict semantics, automatic parallelisation, and efficient array handling. SISAL outputs a dataflow graph in Intermediary Form 1 (IF1). It was derived from VAL, and adds recursion and finite streams. It has a Pascal-like syntax and was designed to be a common high-level language for numerical programs on a variety of multiprocessors.
Implementations exist for the Cray X-MP, Cray Y-MP, Cray-2, Sequent Computer Systems, Encore Alliant, dataflow architectures, transputers and systolic arrays.