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.
But I have to agree, from a novice eye at least, result builders look to be a feature added to support SwiftUI and limited other use cases. Have you seen many examples of third party libraries successfully using them?
And while we're here, do the introduction of macros in Swift 5.9 allow room for replacing result builders with something more uniformly useful?