From 21c688d4f96f6f268c83a55f49073b5d611570d8 Mon Sep 17 00:00:00 2001
From: Stephen Paul Weber <singpolyma@singpolyma.net>
Date: Sat, 6 Apr 2019 21:25:29 -0500
Subject: [PATCH] Update to new UnionType selection semantics

---
 lib/dhall/ast.rb       | 15 ++++++++++++---
 lib/dhall/normalize.rb |  3 ++-
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/lib/dhall/ast.rb b/lib/dhall/ast.rb
index eadb0c8..cef6e7c 100644
--- a/lib/dhall/ast.rb
+++ b/lib/dhall/ast.rb
@@ -607,6 +607,16 @@ module Dhall
 			selector ::String
 		end)
 
+		def call(value)
+			if record.is_a?(UnionType)
+				type = record.alternatives.fetch(selector)
+				body = Union.from(record, selector, Variable[selector])
+				Function.new(var: selector, type: type, body: body).call(value)
+			else
+				super
+			end
+		end
+
 		def as_json
 			[9, record.as_json, selector]
 		end
@@ -659,9 +669,8 @@ module Dhall
 		end
 
 		def fetch(k, default=nil)
-			if (type = alternatives.fetch(k))
-				body = Union.from(self, k, Variable[k])
-				Function.new(var: k, type: type, body: body).normalize
+			if alternatives.fetch(k)
+				super(k)
 			else
 				Union.from(self, k, nil)
 			end
diff --git a/lib/dhall/normalize.rb b/lib/dhall/normalize.rb
index 0eed75b..9870354 100644
--- a/lib/dhall/normalize.rb
+++ b/lib/dhall/normalize.rb
@@ -52,7 +52,8 @@ module Dhall
 			return normalized.fuse if normalized.fuse
 
 			if normalized.function.is_a?(Builtin) ||
-			   normalized.function.is_a?(Function)
+			   normalized.function.is_a?(Function) ||
+			   normalized.function.is_a?(RecordSelection)
 				return normalized.function.call(normalized.argument)
 			end
 
-- 
2.34.5