Hypertextual concurrent control of a Lisp Kernel

Using the Trellis human/computer interaction model as an implementation vehicle, we demonstrate how to use concurrency-supporting hypertext to provide visual displays of the execution ows through a parallel Lisp program. In addition to displays, the hypertext interface allows injection of control ow into an otherwise functional computation, and therefore provides reader control over the order of evaluation of expressions. The resulting system, termed Trellis, can be thought of as a concurrent control ow browser for composing functional computations, providing a visual implementation of kernel-control decomposition. The advantages of Trellis are ease of exploring program side eeects; ease of debugging parallel code; aid in teaching functional languages; and the ability to construct hypertext documents that have parallel execution semantics and exible browsing behaviors.