From bca4d8af659fa84f220a35ec9b7b2d040d374dc9 Mon Sep 17 00:00:00 2001
From: Stephen Paul Weber <singpolyma@singpolyma.net>
Date: Tue, 19 Mar 2019 22:10:56 -0500
Subject: [PATCH] Flatten/unfill applications and builtins when encoding

---
 lib/dhall/ast.rb      | 15 ++++++++++++++-
 lib/dhall/builtins.rb | 16 +++++++++++++++-
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/lib/dhall/ast.rb b/lib/dhall/ast.rb
index 38f1021..823aa42 100644
--- a/lib/dhall/ast.rb
+++ b/lib/dhall/ast.rb
@@ -111,8 +111,21 @@ module Dhall
 			argument Expression
 		end)
 
+		def flatten
+			f, args = if function.is_a?(Application)
+				function.flatten
+			elsif function.is_a?(Builtin) && (unfilled = function.unfill).is_a?(Application)
+				unfilled.flatten
+			else
+				[function, []]
+			end
+
+			[f, args + [argument]]
+		end
+
 		def as_json
-			[0, function.as_json, argument.as_json]
+			function, arguments = flatten
+			[0, function.as_json, *arguments.map(&:as_json)]
 		end
 	end
 
diff --git a/lib/dhall/builtins.rb b/lib/dhall/builtins.rb
index 25844ce..f1ee321 100644
--- a/lib/dhall/builtins.rb
+++ b/lib/dhall/builtins.rb
@@ -13,8 +13,22 @@ module Dhall
 			end
 		end
 
+		def unfill
+			attributes.reduce(self.class.new) do |f, attr|
+				if send(attr.name).nil?
+					f
+				else
+					Application.new(function: f, argument: send(attr.name))
+				end
+			end
+		end
+
 		def as_json
-			self.class.name.split(/::/).last.gsub(/_/, "/")
+			if (unfilled = unfill).class != self.class
+				unfilled.as_json
+			else
+				self.class.name.split(/::/).last.gsub(/_/, "/")
+			end
 		end
 
 		protected
-- 
2.34.5