The framing of the builder pattern as primarily a Rust feature, and fluent interfaces as primarily an OO feature, is a bit odd. A prime example of non-builder

The framing of the builder pattern as primarily a Rust feature, and fluent interfaces as primarily an OO feature, is a bit odd. A prime example of non-builder fluent interfaces are containers in Rust. Both builders and fluent interfaces exist pretty much in all languages that can support chaining methods on some sort of object. This includes OO languages as well as totally-not-OO languages like Rust that just stop short of calling their classes "classes."