flowFromIterable

flowFromIterable is a function found in several reactive and coroutine-based libraries that creates a Flow-like stream from a given Iterable collection. It produces a cold, single-subscription stream, emitting the elements of the iterable in their defined iteration order. The flow remains inactive until a collector subscribes.

Behavior and semantics: flowFromIterable iterates the source lazily and emits each element via the flow’s emission mechanism. If the iterable raises an exception during iteration, the flow signals an error to the collector. The emission can be cancelled by the downstream, in which case the iteration is halted and no further elements are produced. When all elements have been emitted, the flow completes normally.

Performance and usage considerations: The usual implementation consumes elements one by one, so memory usage is typically constant with respect to the emitted items, apart from the overhead of the iterable itself. If the iterable is finite, the flow completes after all elements are emitted; if it is infinite, the flow remains ongoing until cancelled. The function does not inherently duplicate elements or apply buffering beyond what the downstream pipeline specifies. In practice, flowFromIterable integrates with other Flow operators for mapping, filtering, and backpressure-aware processing.

Relation to other APIs: Similar functionality exists in other ecosystems, such as Flux.fromIterable or Flowable.fromIterable in reactive libraries, or asFlow on Iterable in Kotlin coroutines, which converts a collection into a Flow. flowFromIterable is one naming convention used to express this bridge from imperative collections to reactive streams.

Typical use cases: flowFromIterable is useful for adapting existing collections to reactive pipelines, enabling downstream operators to process items reactively, handle errors, and apply backpressure-aware transformations. It is commonly used when a consumer needs to consume a known set of items in order without upfront buffering.