From 2dbfd51f1539998495b93825b7e766b7cce0affd Mon Sep 17 00:00:00 2001
From: Rob Rix <rob.rix@github.com>
Date: Thu, 15 Oct 2015 11:45:40 -0400
Subject: [PATCH] Recur through pairs of `.Keyed` nodes with equal keys.

---
 prototype/Doubt/Interpreter.swift | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/prototype/Doubt/Interpreter.swift b/prototype/Doubt/Interpreter.swift
index aec1cb0a9..d11a5eb65 100644
--- a/prototype/Doubt/Interpreter.swift
+++ b/prototype/Doubt/Interpreter.swift
@@ -29,6 +29,9 @@ public struct Interpreter<Term: TermType> {
 			case let (.Indexed(a), .Indexed(b)) where a.count == b.count:
 				return recur(f(.Indexed(zip(a, b).map(run))))
 
+			case let (.Keyed(a), .Keyed(b)) where Array(a.keys) == Array(b.keys):
+				return recur(f(.Keyed(Dictionary(elements: b.keys.map { ($0, self.run(a[$0]!, b[$0]!)) }))))
+
 			default:
 				return nil
 			}