What is "multilisp"

MultiLisp was a functional programming language and dialect of Scheme, extended with constructs for parallel execution and shared memory. These extensions involve side effects, rendering MultiLisp non-deterministic. In addition to its parallel-programming extensions, MultiLisp also had some unusual garbage collection and task scheduling algorithms. Like Scheme, MultiLisp was oriented toward symbolic computation. Unlike some parallel programming languages, MultiLisp incorporated constructs for causing side effects and for explicitly introducing parallelism.

It was designed by Robert H. Halstead in the early 1980s for use on the 32-processor Concert multiprocessor being developed at MIT and implemented in Interlisp. It has influenced the development of the Scheme dialect Gambit 1, and Interlisp-VAX.