5 files changed, 16 insertions(+), 47 deletions(-)

M lib/dhall/ast.rb
M lib/dhall/binary.rb
M lib/dhall/normalize.rb
M lib/dhall/parser.rb
M lib/dhall/typecheck.rb

@@ 1784,10 1784,10 @@ module Dhall
 
 		def flatten
 			flattened = body.is_a?(LetIn) ? body.flatten : body
-			if flattened.is_a?(LetIn) || flattened.is_a?(LetBlock)
-				LetBlock.for(lets: [let] + flattened.lets, body: flattened.body)
+			if flattened.is_a?(LetBlock)
+				LetBlock.new(lets: lets + flattened.lets, body: flattened.body)
 			else
-				self
+				LetBlock.new(lets: lets, body: body)
 			end
 		end
 


@@ 1810,28 1810,16 @@ module Dhall
 		end
 
 		def as_json
-			[25, *let.as_json, body.as_json]
+			flatten.as_json
 		end
 	end
 
-	class LetBlock < Expression
+	class LetBlock
 		include(ValueSemantics.for_attributes do
-			lets Util::ArrayOf.new(Let, min: 2)
+			lets Util::ArrayOf.new(Let)
 			body Expression
 		end)
 
-		def self.for(lets:, body:)
-			if lets.length == 1
-				LetIn.new(let: lets.first, body: body)
-			else
-				new(lets: lets, body: body)
-			end
-		end
-
-		def flatten
-			unflatten.flatten
-		end
-
 		def unflatten
 			lets.reverse.reduce(body) do |inside, let|
 				letin = LetIn.new(let: let, body: inside)


@@ 1839,10 1827,6 @@ module Dhall
 			end
 		end
 
-		def desugar
-			unflatten(&:desugar)
-		end
-
 		def as_json
 			[25, *lets.flat_map(&:as_json), body.as_json]
 		end

@@ 268,18 268,18 @@ module Dhall
 		end
 	end
 
-	class LetBlock
+	class LetIn
 		def self.decode(*parts)
 			body = Dhall.decode(parts.pop)
-			lets = parts.each_slice(3).map do |(var, type, assign)|
+			parts.each_slice(3).map { |(var, type, assign)|
 				Let.new(
 					var:    var,
 					assign: Dhall.decode(assign),
 					type:   type.nil? ? nil : Dhall.decode(type)
 				)
+			}.reverse.reduce(body) do |inside, let|
+				LetIn.new(let: let, body: inside)
 			end
-
-			self.for(lets: lets, body: body)
 		end
 	end
 


@@ 341,7 341,7 @@ module Dhall
 		nil,
 		nil,
 		Import,
-		LetBlock,
+		LetIn,
 		TypeAnnotation,
 		ToMap,
 		EmptyList

@@ 452,20 452,6 @@ module Dhall
 		end
 	end
 
-	class LetBlock
-		def normalize
-			desugar.normalize
-		end
-
-		def shift(amount, name, min_index)
-			unflatten.shift(amount, name, min_index)
-		end
-
-		def substitute(svar, with_expr)
-			unflatten.substitute(svar, with_expr)
-		end
-	end
-
 	class TypeAnnotation
 		def normalize
 			value.normalize

@@ 31,10 31,11 @@ module Dhall
 			end
 
 			def let_binding
-				LetBlock.for(
-					lets: captures(:let_binding).map(&:value),
-					body: capture(:expression).value
-				)
+				captures(:let_binding).reverse.reduce(
+					capture(:expression).value
+				) do |inside, let|
+					LetIn.new(let: let.value, body: inside)
+				end
 			end
 
 			def lambda

@@ 931,8 931,6 @@ module Dhall
 			end
 		end
 
-		TypeChecker.register ->(blk) { LetIn.for(blk.unflatten) }, Dhall::LetBlock
-
 		class LetIn
 			TypeChecker.register self, Dhall::LetIn