From bebcbdd000b55fa86df4c3c30b6ec7c85ff2dfab Mon Sep 17 00:00:00 2001
From: Case Duckworth
Date: Fri, 5 Apr 2024 13:38:22 -0500
Subject: Fix reading from files ... i'm PRETTY sure

---
 read.lua | 56 +++++++++++++++++++++-----------------
 repl.lua | 95 ++++++++++++++++++++++++++++++++++++----------------------------
 2 files changed, 84 insertions(+), 67 deletions(-)

diff --git a/read.lua b/read.lua
index 4fb9b70..35f5b57 100644
--- a/read.lua
+++ b/read.lua
@@ -7,10 +7,31 @@ local pop = require("util").pop
 
 -- TODO:
 -- - string reading
--- - # syntax
--- - comments
 -- - probably more
 
+m.eof = setmetatable({}, {
+		__type = "EOF",
+		__tostring = function () return "#<eof>" end,
+})
+
+local function inport_next_token (port)
+	local tok, toktype
+	while true do
+		if #port.line == 0 then
+			if port.file then
+				local ln = port.file:read()
+				if ln == nil then return m.eof end
+				port.line = m.tochars(ln)
+			else
+				return nil
+			end
+		end
+		tok, toktype, port.line = m.scan(port.line)()
+		port.line = port.line or {}
+		if tok ~= nil then return tok, toktype end
+	end
+end
+
 function m.inport (source, kind)
 	-- KIND can be one of "file", "string"; defaults to "file"
 	-- SOURCE is the name of the file or the string to read, or nil; if nil,
@@ -18,9 +39,9 @@ function m.inport (source, kind)
 	local f, l
 	local k = kind or "file"
 	if source then
-		if kind == "file" then
+		if k == "file" then
 			f = io.open(source, "r")
-		elseif kind == "string" then
+		elseif k == "string" then
 			l = m.tochars(source)
 		end
 	else
@@ -29,25 +50,10 @@ function m.inport (source, kind)
 	end
 	local t = {
 		file = f,
+		filename = source,
+		kind = kind,
 		line = l or {},
-		next_token =
-			function (self)
-				local tok, toktype
-				while true do
-					if #self.line == 0 and self.file then
-						self.line = m.tochars(
-							self.file:read("*l"))
-					end
-					if not self.line or #self.line == 0 then
-						return nil
-					end
-					tok, toktype, self.line =
-						m.scan(self.line)()
-					if tok ~= nil then
-						return tok, toktype
-					end
-				end
-			end,
+		next_token = inport_next_token,
 	}
 	if t.file then t.close = function (self) self.file:close() end; end
 	local mt = {
@@ -232,12 +238,12 @@ m.readmacros = {
 			table.insert(Q, m.read(port))
 			return t.list(Q)
 		end,
-	comment = idf(nil),
+	comment = idf(nil)
 }
 
 function m.read (port)
 	local function read_ahead (tok, toktype)
-		if tok == nil then error("Unexpected EOF") end
+		if tok == m.eof then error("Unexpected EOF") end
 		if toktype == "open" then
 			local L = {}
 			while true do
@@ -262,7 +268,7 @@ function m.read (port)
 	end
 	-- body of read
 	local tok1, toktype1 = port:next_token()
-	if tok1 == nil then return nil
+	if tok1 == m.eof then return m.eof
 	else return read_ahead(tok1, toktype1)
 	end
 end
diff --git a/repl.lua b/repl.lua
index be739c7..86bc0af 100644
--- a/repl.lua
+++ b/repl.lua
@@ -1,9 +1,10 @@
 --- lam.repl
 
 local m = {}
-local read = require("read")
-local eval = require("eval")
-local pp = require("dump").pp
+local _r = require("read")
+local read, inport, read_string, eof =
+	_r.read, _r.inport, _r.read_string, _r.eof
+local eval = require("eval").eval
 
 local function schemeprint (x)
 	-- if x == nil then return end
@@ -12,7 +13,7 @@ local function schemeprint (x)
 	elseif x == false then
 		print("#f")
 	elseif x == nil then
-		print("#n")
+		print("#<nil>")
 	else
 		print(x)
 	end
@@ -26,57 +27,67 @@ local lam = [[
  -------------
 ]]
 
-function m.repl (prompt, infile, out)
-	-- PROMPT should be a string, INFILE is a filename, and OUT is either a
-	-- filename, nil (in which case it will be stdout), or false (which
-	-- suppresses output)
-	local inport = read.inport(infile)
-	if out ~= false then
-		io.output(out)
+local function handle_error (e)
+	local start = e:find(": ")
+	return e:sub(start + 2)
+end
+
+function m.read_eval (filename, interactive)
+	-- interactive = { out = file or handle, prompt = string, }
+	local inport = inport(filename)
+	local prompt = interactive and interactive.prompt or "> "
+	if interactive then
+		io.output(interactive.out or io.stdout)
 		io.write(lam)
+		io.output():setvbuf("line")
+	else
+		io.output(io.stdout) -- hmmm
+		io.output():setvbuf("no")
 	end
-	io.output():setvbuf("line")
-	if prompt then
-		stderr = io.open("/dev/stderr", "w") -- Linux-only !
-	end
-	while true do -- loop
-		if prompt then
-			stderr:write(prompt)
-			stderr:flush()
+	repeat
+		if interactive then
+			io.stderr:write(prompt)
+			io.stderr:flush()
 		end
 		-- read
 		local ok, x = xpcall(
-			function () return read.read(inport) end,
-			function (e)
-				local start = e:find(": ")
-				return e:sub(start+2)
-			end
+			function ()
+				local nxt = read(inport)
+				return nxt
+			end,
+			handle_error
 		)
 		if not ok then
-			print("(read) not ok: " .. x)
-			x = nil
+			io.stderr:write("(read) not ok: ", x, "\n")
+			-- in interactive mode, errors should not be fatal.  in
+			-- batch mode, they should be.
+			if not interactive then return nil end
 		end
 		-- eval
-		if x then
-			local ok, val =
-				xpcall(
-					function () return eval.eval(x) end,
-					function (e)
-						local start = e:find(": ")
-						return e:sub(start+2)
-					end
-				)
+		if ok then
+			local ok, v = xpcall(
+				function () return eval(x) end,
+				handle_error
+			)
 			if not ok then
-				print("(eval) not ok: " .. val)
-			elseif out ~= false then
-				-- print
-				schemeprint(val)
+				io.stderr:write("(eval) not ok: ", v, "\n")
+				if not interactive then return nil end
 			end
+			-- print
+			if ok and interactive then schemeprint(v) end
+		elseif interactive then
+			ok = "recover"
 		end
-	end
+	until x == eof -- loop
 	inport:close()
-	stderr:close()
-	io.output():close()
+end
+
+function m.repl (prompt)
+	return m.read_eval(nil, { prompt = prompt, })
+end
+
+function m.load (filename)
+	return m.read_eval(filename)
 end
 
 --------
-- 
cgit 1.4.1-21-gabe81