Type checking Swift, in reasonable time

The design of Swift's type checker is somewhat unusual among programming languages, because it combines constraint solving with type-based overloading. This allows for expressive API design, but it also introduces some challenges with performance and diagnostics. As is well-known, in the worst case, this kind of constraint system problem takes exponential time to solve. On the other hand, there is much one can do to improve performance on "realistic" inputs. In this talk, I will discuss the design of Swift's constraint solver, outline some recent improvements made in Swift 6.2 and 6.3, and talk about the roadmap for future improvements. Speaker Bio Slava Pestov is a Swift compiler developer at Apple, having spent much of the last ten years improving Swift's type checker and implementation of generics. Slava enjoys playing around with abstract algebra and its many connections to computer science. Prior to joining the Swift team, Slava led the development of the Factor programming language (https://factorcode.org) and the jEdit text editor (https://jedit.org).