2 files changed, 8 insertions(+), 5 deletions(-)

M dhall-lang
M lib/dhall/builtins.rb

@@ 1,1 1,1 @@
-Subproject commit 1ed98c33ce5078161109885f0b16b3828958f4e2
+Subproject commit fd39a0d6db4a276cbdd6ab1f14b58c8330ad88da

@@ 102,10 102,9 @@ module Dhall
 			protected
 
 			def uncurried_call(x, y)
-				if Natural_isZero.new.call(x) === true ||
-				   Natural_isZero.new.call(y) === true
-					return y
-				end
+				return y if zero?(x) || zero?(y)
+
+				return Dhall::Natural.new(value: 0) if x == y
 
 				unless x.is_a?(Dhall::Natural) && y.is_a?(Dhall::Natural)
 					return unfill(x, y)


@@ 113,6 112,10 @@ module Dhall
 
 				Dhall::Natural.new(value: [y.to_i - x.to_i, 0].max)
 			end
+
+			def zero?(x)
+				Natural_isZero.new.call(x) === true
+			end
 		end
 
 		class Natural_even < BuiltinFunction