From 65a1c1f8820425e5a531a1bd4d652390489d4f9c Mon Sep 17 00:00:00 2001
From: Case Duckworth
Date: Wed, 21 Feb 2024 22:20:45 -0600
Subject: Fix weird eval problem

Don't do things ya don't get, kids
---
 eval.lua | 95 ++++++++++++++++++++++++++++++++++++----------------------------
 1 file changed, 54 insertions(+), 41 deletions(-)

(limited to 'eval.lua')

diff --git a/eval.lua b/eval.lua
index 3decded..d441859 100644
--- a/eval.lua
+++ b/eval.lua
@@ -2,36 +2,53 @@
 
 local eval = {}
 local read = require "read"
-local types = require "types"
 local util = require "util"
 local pp = require "pp"
 
-Env = types.Object:new {
-	__type = "Environment",
-	__extend =
-		function(self, parms, args, outer)
-			for _, p in ipairs(parms) do
-				for _, a in ipairs(args) do
-					self[p] = a
-				end
-			end
-			getmetatable(self).__index = outer
-		end,
-}
+local function Type (x)
+	if type(x) == "string" then
+		return "Symbol"
+	elseif type(x) == "number" then
+		return "Number"
+	elseif getmetatable(x) and getmetatable(x).__type then
+		return x.__type
+	elseif type(x) == "table" then
+		return "List"
+	else
+		return type(x)
+	end
+end
 
-Proc = types.Object:new {
-	__type = "Procedure",
-	__call =
-		function (self, args)
-			local e = Env:new()
-			e:__extend(self.parms,
-				   util.table(args),
-				   self.env)
-			return eval(self.body[1], e)
-		end
-}
+local Symbol = tostring
+local Number = tonumber
+
+local function Env(inner, outer)
+	return setmetatable(inner, { __type = "Environment", __index = outer, })
+end
+
+local function Proc(params, body, env)
+	local p = {
+		params = params,
+		body = body,
+		env = env,
+	}
+	local mt = {
+		__type = "Procedure",
+		__call =
+			function (self, ...)
+				local inner = {}
+				for _, p in ipairs(self.params) do
+					for _, a in ipairs({...}) do
+						inner[p] = a
+					end
+				end
+				return eval(self.body, Env(inner, self.env))
+			end,
+	}
+	return setmetatable(p, mt)
+end
 
-global_env = Env:new {
+local global_env = {
 	-- constants
 	["#t"] = true,
 	["#f"] = false,
@@ -56,11 +73,11 @@ global_env = Env:new {
 		end,
 	["number?"] =
 		function(x)
-			return types.Type(x) == "Number"
+			return Type(x) == "Number"
 		end,
 	["symbol?"] =
 		function(x)
-			return types.Type(x) == "Symbol"
+			return Type(x) == "Symbol"
 		end,
 	-- scheme functions
 	["apply"] =
@@ -95,9 +112,9 @@ end
 
 function eval.eval (x, env)
 	env = env or global_env
-	if types.Type(x) == "Symbol" then
+	if Type(x) == "Symbol" then
 		return env[x]
-	elseif types.Type(x) ~= "List" then
+	elseif type(x) ~= "table" then
 		return x
 	else
 		local op = util.car(x)
@@ -107,19 +124,15 @@ function eval.eval (x, env)
 		elseif op == "define" then
 			local sym, exp = table.unpack(args)
 			env[sym] = eval(exp, env)
-		elseif op == "set!" then
-			local sym, exp = table.unpack(args)
-			env[sym] = eval(exp, env)
+			--[[
+				elseif op == "set!" then
+				local sym, exp = table.unpack(args)
+				env[sym] = eval(exp, env) --]]
 		elseif op == "lambda" then
-			local parms = util.car(args)
-			local body = util.cdr(args)
-			return Proc:new {
-				parms = parms,
-				body = body,
-				env = env,
-			}
+			local params = util.car(args)
+			local body = util.cdr(args)[1]
+			return Proc(params, body, env)
 		else		-- procedure call
-			pp(op)
 			local proc = eval(op, env)
 			local vals = util.map(
 				function(v) return eval(v, env) end,
@@ -142,4 +155,4 @@ return setmetatable(eval, { __call =
 
 --[[
 	(begin (define sq (lambda (x) (* x x))) (define rep (lambda (f) (lambda (x) (f (f x))))))
--- ]]
+	-- ]]
-- 
cgit 1.4.1-21-gabe81