Modulewhile

Modulewhile is a hypothetical programming construct that combines modular scope with a while loop. It is designed to execute an iterative process while keeping the loop’s internal state contained within a module boundary, exposing a fixed interface to the outer program. In languages or proposals that support modular scoping, a modulewhile loop uses a private module to store state that is not directly accessible from the surrounding code, helping to prevent unintended interactions.

The main purpose of modulewhile is to improve encapsulation, reusability, and safe composition of looping logic. By confining state to a module, it reduces side effects and makes it easier to reason about complex iterative algorithms. The module typically defines a small interface for external control or observation, while the loop body can freely update the module’s internal state.

Semantics of modulewhile vary by language, but common ideas include: a module is instantiated at the start of the loop and its state persists across iterations; the loop condition is evaluated against the module’s state; the body modifies internal state, potentially exporting results through the module’s interface; and conventional loop controls such as break or continue may be supported either directly or via module-defined signals.

Syntax, in proposed forms, resembles a standard while loop but scoped within a module. A typical form is modulewhile (condition) do ... end, with differences depending on the host language’s module and visibility rules. Use cases include streaming data processing, state machines, and reusable iterator patterns that benefit from strict state encapsulation.

Notes and history: modulewhile remains primarily a design concept discussed in language-design literature, not a widely adopted standard. It is often contrasted with implementing similar patterns through closures and local modules. See also: modules, while loops, encapsulation.