Shuttle: A Lightweight Go Library for Reusable Comparators, Predicates, and Streams

A new open-source Go module called Shuttle has been released to address code duplication when sharing sorting, filtering, and traversal logic across multiple call sites. The library provides four focused packages — comparator, predicate, optional, and stream — each built around named, type-safe function types that compose through standard Go assignability. Streams are lazy and sequential, built on top of iter.Seq[T], and only begin traversal when a terminal operation such as Collect or MaxBy is called. Shuttle carries no third-party runtime dependencies and deliberately omits broader features like parallel operators, I/O sources, or an error-carrying stream to keep its scope narrow. An included example program demonstrates nested flat-mapping across animal taxonomy data, illustrating how the four abstractions work together in practice.