SE-0157 "Recursive constraints" is implemented in Swift 4.1

Author: DougGregor

proposals/0157-recursive-protocol-constraints.md

@@ -3,7 +3,7 @@
 * Proposal: [SE-0157](0157-recursive-protocol-constraints.md)
 * Authors: [Douglas Gregor](https://github.com/DougGregor), [Erica Sadun](https://github.com/erica), [Austin Zheng](https://github.com/austinzheng)
 * Review Manager: [John McCall](https://github.com/rjmccall)
-* Status: **Accepted**
+* Status: **Implemented (Swift 4.1)**
 * Decision Notes: [Rationale](https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20170320/034266.html)
 * Bug: [SR-1445](https://bugs.swift.org/browse/SR-1445)