Forward scan matching for trailing closures

Swift 5.3 extended trailing closure syntax, allowing additional labeled trailing closures to follow an initial un-labeled trailing closure. In this Swift evolution pitch, Doug Gregor from the Swift Core Team proposes an improvement to how the Swift compiler scans and matches trailing closure arguments to parameters. This is a source-breaking change, but Doug believes that it's worth doing now to get an improved scanning model sooner.

Introduce AnonymousKeyPath

In this evolution pitch from the Swift forums, Shai Mishali suggests the introduction of a new kind of KeyPath - AnonymousKeyPath. The idea here is that the key path can be used without knowing the Root of the KeyPath, but rather only the Value constrained to it. Although it's an interesting suggestion, the discussion that follows the pitch indicates that the problem it solves can be solved in other, more effective ways.

Returning to an old hobbyhorse: Migrating higher order function names to comply with API guidelines

A higher order function is a function which takes a function as an argument, or returns a function. In this post from the Swift forums, Erica Sadun pitches a proposal to rename Swift's higher order functions, such as map and filter, based on the Swift API design guidelines. It's something which can be done without causing breaking changes, and I am in favour of the proposal.