pipeable

Pipeable describes a programming style in which functions are designed to be composed using a pipe or pipe-like operator. Pipeable functions are typically pure, with no hidden side effects, and operate on an input value to produce an output. This design favors readable, declarative data transformations assembled as a sequence.

In functional programming and libraries, pipeable utilities are small, reusable functions that can be linked together from left to right. They are often implemented as separate units and used with a pipe function or operator, rather than being called in a nested or pointful style. The emphasis is on modularity and straightforward data flow through a pipeline.

In reactive programming such as RxJS, pipeable operators are a category of functions that transform observables. They are consumed by a pipe method on an observable, enabling concise pipelines like map, filter, and reduce to be composed into a single flow. This avoids nesting and improves readability by keeping transformations in a linear sequence.

Terminology varies; some communities reserve pipeable for libraries that expose operators as standalone functions to be piped, while others use "pipeable" more generally for any function designed for piping. The concept is closely related to function composition and currying, and it is widely used to promote modular, testable, and maintainable code.