pushtype

Pushtype is a term used in theoretical computer science and in some programming libraries to denote a data type that represents a push-based data producer. Unlike pull-based types, where a consumer requests data, a pushtype assumes that data is produced and delivered to consumers as soon as it is available. It is often used to model event streams, asynchronous data sources, and other reactive or concurrent systems.

Formalization and interface

In languages with functional types, a pushtype for a value of type A can be modeled as Push<A> = (A -> void) -> void. This means a pushtype is a function that accepts a consumer callback to receive values and returns a cancellation handle or a termination signal. A minimal interface typically includes a run or start method that accepts a consumer, and an optional cancel or dispose method for cleanup. Pushtypes can also support optional buffering or backpressure strategies to control the flow of data.

Operations and composition

Pushtypes are designed to be composable. Common operations include map (to transform produced values), flatMap or chain (to sequence asynchronous steps), and merge or concat (to combine multiple pushtypes). They can be implemented as higher-order abstractions around event sources, enabling modular construction of complex data pipelines.

Relation to other concepts

Pushtype shares similarities with observables and publishers, but emphasizes producer-driven delivery. It is distinct from promises or futures, which resolve a single value, by representing potentially multiple values delivered over time. In practice, pushtypes appear in libraries that model event streams, UI events, or sensor data in a push-oriented style.

Usage considerations

Pushtypes can simplify certain asynchronous designs but require careful handling of lifecycle, backpressure, and resource cleanup to avoid leaks. They are most useful when a system benefits from decoupled producers and consumers with clear data-flow semantics. See also: observable, publisher-subscriber, stream.