local pprint=require"pprint"
pprint.setup{show_all=true,use_tostring=true}

local repl_env = {}


local function reload(modname)
	local oldmod = require(modname)
	assert(type(oldmod) == "table","reloading only works on modules that return tables")
	package.loaded[modname] = nil
	local newmod = require(modname)
	package.loaded[modname]=oldmod
	assert(type(newmod) == "table","new module doesn't seem to be a table, cancelling")
	for k in pairs(oldmod) do oldmod[k] = nil end
	for k,v in pairs(newmod) do oldmod[k] = v end
end

-- should use loadstring on 5.1
-- works on luajit though
local function load_chunk(s)
	return load(s,"repl","t")
end

local function prompt(p)
	io.write(p)
	return io.read()
end

local function read_chunk()
	-- try with return
	-- if that doesn't work try without return
	-- if error ends in <eof> try multiline

	local function try(text)
		if text:sub(1,3) == ",r " then
			return function() reload(text:sub(4)) print("reloaded "..text:sub(4)) end
		end

		local f, err = load_chunk("return "..text..";")
		if f then return f end

		local f, err = load_chunk(text)
		if f then return f end

		if err:sub(-5) == "<eof>" or err:sub(-7) == "'<eof>'" then
			local nt = text.."\n"..prompt("} ")
			return try(nt)
		end

		return f, err
	end
	return try(prompt("] "))
end

local function result(ok,...)
	if ok then
		pprint(...)
	else
		print("error: "..(...))
	end
end

while true do
	local f,err = read_chunk()

	if not f then
		print("load error: "..err)
	else
		result(xpcall(f,function(e) return debug.traceback(e,1) end))
	end
end