Result builders are pretty popular in third party libraries, too. There's good use of them in Pointfree's libraries Parsing (https://github.com/pointfreeco/swift-parsing) and Composable Architecture (https://pointfreeco.github.io/swift-composable-architecture/...).

A quick search in the package index also finds things like these:

- https://swiftpackageindex.com/davidcaddy/DCSettings

- https://swiftpackageindex.com/tdeleon/relax/2.1.0/documentat...

- https://swiftpackageindex.com/mkj-is/PathBuilder

- https://swiftpackageindex.com/Saelyria/Artemis

- https://swiftpackageindex.com/FluidGroup/MondrianLayout

etc.