Loopdriven

Loopdriven is a software design concept describing systems where control flow and state progression are primarily driven by loops and iterative constructs rather than by events, callbacks, or reactive streams. In a loopdriven program, the main loop serves as the central conductor; within each iteration, a sequence of steps updates state, performs I/O, and decides whether to continue or terminate. The design emphasizes explicit sequencing, deterministic progression, and clear loop invariants.

The term appears in theoretical discussions and among practitioners exploring alternatives to event-driven architectures. It is not part of a formal standard, and implementations vary widely in terminology and granularity.

Core principles include: operating within a bounded or well-defined loop; maintaining explicit invariants that hold across iterations; ensuring termination conditions are checked each cycle; modularizing work into clearly delimited loop bodies; and handling I/O and external interactions in a controlled, synchronous fashion when appropriate. Variants range from fixed-iteration loops to while-based progress loops and nested loops used to model sub-states.

Benefits of loopdriven design often cited are improved predictability, easier reasoning about state transitions, and simpler unit testing for certain workloads. Challenges include potential for long-running or unresponsive loops in interactive environments, difficulties integrating with asynchronous I/O or concurrent tasks, and the risk of monolithic structures if not carefully modularized.

Applications include embedded control systems, simulations, batch data processing, and some numerical or scientific computing contexts where deterministic sequencing is desirable.

See also: loop, while loop, finite state machine, event-driven programming, state machine.