destinationwhile

Destinationwhile is a term used in theoretical discussions of programming language design to describe a loop-like control-flow construct that targets a specific destination or component during iteration. Unlike a plain while loop, destinationwhile couples the continuation condition with an explicit destination, guiding where control should be directed after each iteration. The concept is often explored in the context of distributed or dataflow-style languages where work units move between subsystems.

In practice, destinationwhile envisions a loop that executes while a condition remains true, but the body of the loop is designed to interact with or send progress to a designated destination. This destination can be a particular service, thread, or communication channel. The mechanism supports asynchronous or cooperative scheduling by allowing the loop to yield or transfer control to the target destination as part of each iteration, rather than simply returning to a local continuation.

A typical destinationwhile construct would specify both the destination and the condition. For example, a pseudo-syntax might be: destinationwhile destination = WorkerA when not isComplete(destination) { performStep(destination); pollProgress(destination) }. The loop continues as long as the condition is true, with the destination serving as the locus of coordination or state updates. Variants may include timeouts, max-iteration limits, or explicit yields to the destination to accommodate heterogeneous execution environments.

Use cases discussed in literature include modeling asynchronous task pipelines, distributed workflows, and data-processing graphs where progress naturally tracks to a particular component. However, destinationwhile is not part of a standardized language specification, and its exact syntax and semantics vary across theoretical proposals.

See also: while loop, dataflow programming, distributed systems, cooperative multitasking.