From b561310f04f8e0b358b39679da096e1d5eb953aa Mon Sep 17 00:00:00 2001
From: Stephen Paul Weber <singpolyma@singpolyma.net>
Date: Wed, 8 May 2019 14:09:04 -0500
Subject: [PATCH] as_dhall for Proc

Cannot actually serialize this, but can be useful for passing functions
in to Dhall functions, etc.
---
 lib/dhall/as_dhall.rb  |  6 ++++++
 lib/dhall/ast.rb       | 22 ++++++++++++++++++++++
 lib/dhall/normalize.rb | 13 +++++++++++--
 3 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/lib/dhall/as_dhall.rb b/lib/dhall/as_dhall.rb
index e40a0a1..f1ff8f1 100644
--- a/lib/dhall/as_dhall.rb
+++ b/lib/dhall/as_dhall.rb
@@ -220,5 +220,11 @@ module Dhall
 				)
 			end
 		end
+
+		refine ::Proc do
+			def as_dhall
+				FunctionProxy.new(self)
+			end
+		end
 	end
 end
diff --git a/lib/dhall/ast.rb b/lib/dhall/ast.rb
index 741a7ec..f70cd92 100644
--- a/lib/dhall/ast.rb
+++ b/lib/dhall/ast.rb
@@ -188,6 +188,28 @@ module Dhall
 		end
 	end
 
+	class FunctionProxy < Function
+		def initialize(callable, curry: true)
+			@callable = if !curry
+				callable
+			elsif callable.respond_to?(:curry)
+				callable.curry
+			elsif callable.respond_to?(:to_proc)
+				callable.to_proc.curry
+			else
+				callable.method(:call).to_proc.curry
+			end
+		end
+
+		def call(*args, &block)
+			@callable.call(*args.map { |arg| arg&.as_dhall }, &block).as_dhall
+		end
+
+		def as_json
+			raise "Cannot serialize #{self}"
+		end
+	end
+
 	class Bool < Expression
 		include(ValueSemantics.for_attributes do
 			value Bool()
diff --git a/lib/dhall/normalize.rb b/lib/dhall/normalize.rb
index ec4df46..0d82b1c 100644
--- a/lib/dhall/normalize.rb
+++ b/lib/dhall/normalize.rb
@@ -120,9 +120,18 @@ module Dhall
 		end
 	end
 
-	class Forall; end
+	class FunctionProxy
+		def shift(*)
+			self
+		end
+
+		def substitute(*)
+			raise "Cannot substitute #{self}"
+		end
 
-	class Bool
+		def normalize
+			self
+		end
 	end
 
 	class Variable
-- 
2.34.2