From 4f4494a9b1057e1807488ed44b05d9fb9ce97b48 Mon Sep 17 00:00:00 2001
From: Case Duckworth
Date: Thu, 21 Mar 2024 17:55:21 -0500
Subject: Implment set!

---
 eval.lua | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/eval.lua b/eval.lua
index f58c36e..9b1c315 100644
--- a/eval.lua
+++ b/eval.lua
@@ -11,6 +11,16 @@ function eval.Env (inner, outer)
 	local mt = {
 		__type = "Environment",
 		__index = outer,
+		__newindex =
+			function (self, key, value)
+				if rawget(self, key) then
+					-- Set the current environment's value
+					rawset(self, key, value)
+				else
+					-- Set the outer value
+					getmetatable(self).__index[key] = value
+				end
+			end,
 	}
 	return setmetatable(inner, mt)
 end
@@ -54,8 +64,10 @@ function eval.eval (x, env)
 		if op == "quote" then
 			return args.car
 		elseif op == "define" or op == "def" then
-			env[args.car] = eval.eval(args.cdr.car, env)
+			rawset(env, args.car, eval.eval(args.cdr.car, env))
 			return nil
+		elseif op == "set!" then
+			env[args.car] = eval.eval(args.cdr.car, env)
 		elseif op == "lambda" or op == "lam" then
 			return eval.Proc(args.car, args.cdr, env)
 		elseif op == "if" then
-- 
cgit 1.4.1-21-gabe81