diff --git a/bin/can b/bin/can
index 2ec98fd..9076123 100644
--- a/bin/can
+++ b/bin/can
@@ -1,4 +1,5 @@
-#!/bin/lua
+#!/usr/bin/env lua
+
 local candran = require("candran")
 local cmdline = require("candran.cmdline")
 
@@ -29,7 +30,13 @@ if arg[#arg] == "-" then
 	f()
 -- file
 elseif #args >= 1 then
-	candran.dofile(args[1], args)
+	local f, err = candran.loadfile(args[1], nil, args)
+	if not f then
+		print("can: "..err)
+		os.exit(1)
+	else
+		f()
+	end
 -- REPL
 else
 	-- Setup linenoise
diff --git a/bin/canc b/bin/canc
index d6fbb6c..c73d368 100644
--- a/bin/canc
+++ b/bin/canc
@@ -1,4 +1,5 @@
-#!/bin/lua
+#!/usr/bin/env lua
+
 local candran = require("candran")
 local cmdline = require("candran.cmdline")
 local parse = require("candran.can-parser.parser").parse
@@ -78,13 +79,28 @@ for _, file in ipairs(args) do
 
 	local out = input
 	if args.preprocess then
-		out = candran.preprocess(out, args)
+		local r, err = candran.preprocess(out, args)
+		if not r then
+			print("canc: "..err)
+			os.exit(1)
+		end
+		out = r
 	end
 	if args.compile then
-		out = candran.compile(out, args)
+		local r, err = candran.compile(out, args)
+		if not r then
+			print("canc: "..err)
+			os.exit(1)
+		end
+		out = r
 	end
 	if args.compile == nil and args.preprocess == nil then
-		out = candran.make(input, args)
+		local r, err = candran.make(input, args)
+		if not r then
+			print("canc: "..err)
+			os.exit(1)
+		end
+		out = r
 	end
 
 	if args.print then
diff --git a/bin/cancheck b/bin/cancheck
new file mode 100644
index 0000000..df59191
--- /dev/null
+++ b/bin/cancheck
@@ -0,0 +1,116 @@
+#!/usr/bin/env lua
+
+-- Monkey patch Luacheck (tested against version 0.23.0) to support Candran files
+local candran = require("candran")
+
+local function pattern(token)
+	return "()"..token:gsub("[^%w]", "%%%0").."()"
+end
+
+local tokenAlias = {
+	["self"] = { "@", ":" }
+}
+
+-- Patch checker
+local oldCheck = require("luacheck.check")
+local function check(can)
+	local lua, err = candran.make(can)
+	if lua then
+		local r = oldCheck(lua)
+		-- Calculate Candran file position.
+		if #r.warnings > 0 then
+			local lua_lines = {}
+			for l in (lua.."\n"):gmatch("([^\n]*)\n") do
+				table.insert(lua_lines, l)
+			end
+			local can_lines = {}
+			for l in (can.."\n"):gmatch("([^\n]*)\n") do
+				table.insert(can_lines, l)
+			end
+			for _, warning in ipairs(r.warnings) do
+				-- candran line
+				local lua_line = lua_lines[warning.line]
+				warning.can_line = tonumber(lua_line:match(".*%-%- .-%:(%d+)$"))
+
+				-- candran column
+				local can_line = can_lines[warning.can_line]
+				local lua_token = lua_line:sub(warning.column, warning.end_column)
+				local token_pattern = pattern(lua_token) -- token finding pattern
+				-- the warning happens on the n-th instance of lua_token on this line
+				local lua_n = 1
+				for start in lua_line:gmatch(token_pattern) do
+					if start >= warning.column then
+						break
+					end
+					lua_n = lua_n + 1
+				end
+				-- Find associated candran token. If lua_n > can_nmax, the last found lua_token is used.
+				-- This approximation should work in like, 90% of cases.
+				local can_n = 1
+				local pos = 1
+				while can_n <= lua_n do
+					-- find first token or alias of this token
+					local start, stop = can_line:match(token_pattern, pos)
+					if tokenAlias[lua_token] then
+						for _, token in ipairs(tokenAlias[lua_token]) do
+							local nstart, nstop = can_line:match(pattern(token), pos)
+							if nstart and (not start or nstart < start) then
+								start, stop = nstart, nstop
+							end
+						end
+					end
+					-- found
+					if start then
+						pos = stop
+						warning.can_column, warning.can_end_column = start, stop
+						can_n = can_n + 1
+					else
+						break
+					end
+				end
+			end
+		end
+		return r
+	else
+		local line, column, msg = err:match(":(%d+):(%d+):%s*(.*)$")
+		local syntax_error = {
+			code = "011",
+			line = line,
+			column = column,
+			end_column = column,
+			msg = msg
+		}
+		return {
+			warnings = {syntax_error},
+			inline_options = {},
+			line_lengths = {},
+			line_endings = {}
+		}
+	end
+end
+package.loaded["luacheck.check"] = check
+
+-- Patch formatter
+local format = require("luacheck.format")
+local function format_location(file, location, opts)
+   local res = ("%s:%d:%d"):format(file, location.can_line or location.line, location.can_column or location.column)
+   if opts.ranges then
+      res = ("%s-%d"):format(res, location.can_end_column or location.end_column)
+   end
+   return res
+end
+local function setupvalue(fn, val, name, ...)
+	for i=1, debug.getinfo(fn, "u").nups do
+		local n, v = debug.getupvalue(fn, i)
+		if n == name then
+			if not ... then
+				debug.setupvalue(fn, i, val)
+			else
+				setupvalue(v, val, ...)
+			end
+		end
+	end
+end
+setupvalue(format.builtin_formatters.plain, format_location, "format_event", "format_location")
+
+require("luacheck.main")
diff --git a/candran.can b/candran.can
index 3bbed3b..2022852 100644
--- a/candran.can
+++ b/candran.can
@@ -11,7 +11,7 @@
 #import("candran.can-parser.parser")
 
 local candran = {
-	VERSION = "0.11.0"
+	VERSION = "0.12.0"
 }
 
 --- Default options.
@@ -37,7 +37,9 @@ end
 --- Run the preprocessor
 -- @tparam input string input code
 -- @tparam options table arguments for the preprocessor. They will be inserted into the preprocessor environement.
--- @treturn output string output code
+-- @treturn[1] output string output code
+-- @treturn[2] nil nil if error
+-- @treturn[2] error string error message
 function candran.preprocess(input, options={})
 	options = util.merge(candran.default, options)
 
@@ -90,10 +92,10 @@ function candran.preprocess(input, options={})
 
 		-- open module file
 		local f = io.open(filepath)
-		if not f then error("Can't open the module file to import") end
+		if not f then error("can't open the module file to import") end
 
 		margs = util.merge(options, { chunkname = filepath, loadLocal = true, loadPackage = true }, margs)
-		local modcontent = candran.preprocess(f:read("*a"), margs)
+		local modcontent = assert(candran.preprocess(f:read("*a"), margs))
 		f:close()
 
 		-- get module name (ex: module name of path.to.module is module)
@@ -113,7 +115,7 @@ function candran.preprocess(input, options={})
 	-- @tparam file string filepath
 	env.include = function(file)
 		local f = io.open(file)
-		if not f then error("Can't open the file "..file.." to include") end
+		if not f then error("can't open the file "..file.." to include") end
 		env.write(f:read("*a"))
 		f:close()
 	end
@@ -131,12 +133,21 @@ function candran.preprocess(input, options={})
 	end
 
 	-- compile & load preprocessor
-	local preprocess, err = util.load(candran.compile(preprocessor, args), "candran preprocessor", env)
-	if not preprocess then error("Error while creating Candran preprocessor: " .. err) end
+	local preprocess, err = candran.compile(preprocessor, options)
+	if not preprocess then
+		return nil, "in preprocessor: "..err
+	end
+
+	preprocess, err = util.load(preprocessor, "candran preprocessor", env)
+	if not preprocess then
+		return nil, "in preprocessor: "..err
+	end
 
 	-- execute preprocessor
 	local success, output = pcall(preprocess)
-	if not success then error("Error while preprocessing file: " .. output) end
+	if not success then
+		return nil, "in preprocessor: "..output
+	end
 
 	return output
 end
@@ -144,14 +155,16 @@ end
 --- Run the compiler
 -- @tparam input string input code
 -- @tparam options table options for the compiler
--- @treturn output string output code
+-- @treturn[1] output string output code
+-- @treturn[2] nil nil if error
+-- @treturn[2] error string error message
 function candran.compile(input, options={})
 	options = util.merge(candran.default, options)
 
 	local ast, errmsg = parser.parse(input, options.chunkname)
 
 	if not ast then
-		error("Compiler: error while parsing file: "..errmsg)
+		return nil, errmsg
 	end
 
 	return require("compiler."..options.target)(input, ast, options)
@@ -160,9 +173,18 @@ end
 --- Preprocess & compile code
 -- @tparam code string input code
 -- @tparam options table arguments for the preprocessor and compiler
--- @treturn output string output code
+-- @treturn[1] output string output code
+-- @treturn[2] nil nil if error
+-- @treturn[2] error string error message
 function candran.make(code, options)
-	return candran.compile(candran.preprocess(code, options), options)
+	local r, err = candran.preprocess(code, options)
+	if r then
+		r, err = candran.compile(r, options)
+		if r then
+			return r
+		end
+	end
+	return r, err
 end
 
 local errorRewritingActive = false
@@ -171,7 +193,9 @@ local codeCache = {}
 -- Will rewrite errors by default.
 function candran.loadfile(filepath, env, options)
 	local f, err = io.open(filepath)
-	if not f then error("can't open the file: "..err) end
+	if not f then
+		return nil, "cannot open %s":format(err)
+	end
 	local content = f:read("*a")
 	f:close()
 
@@ -183,14 +207,19 @@ end
 function candran.load(chunk, chunkname, env, options={})
 	options = util.merge({ chunkname = tostring(chunkname or chunk) }, options)
 
-	codeCache[options.chunkname] = candran.make(chunk, options)
-	local f, err = util.load(codeCache[options.chunkname], options.chunkname, env)
+	local code, err = candran.make(chunk, options)
+	if not code then
+		return code, err
+	end
+
+	codeCache[options.chunkname] = code
+	local f, err = util.load(code, options.chunkname, env)
 
 	-- Um. Candran isn't supposed to generate invalid Lua code, so this is a major issue.
 	-- This is not going to raise an error because this is supposed to behave similarly to Lua's load function.
 	-- But the error message will likely be useless unless you know how Candran works.
 	if f == nil then
-		return f, "Candran unexpectedly generated invalid code: "..err
+		return f, "candran unexpectedly generated invalid code: "..err
 	end
 
 	if options.rewriteErrors == false then
@@ -248,7 +277,7 @@ function candran.messageHandler(message)
 
 		if originalFile then
 			local i = 0
-			for l in originalFile:gmatch("([^\n]*)\n") do
+			for l in (originalFile.."\n"):gmatch("([^\n]*)\n") do
 				i = i +1
 				if i == line then
 					local extSource, lineMap = l:match(".*%-%- (.-)%:(%d+)$")
diff --git a/candran.lua b/candran.lua
index bc6f34a..8ea939c 100644
--- a/candran.lua
+++ b/candran.lua
@@ -299,7 +299,7 @@ local UNPACK = function(list, i, j) -- ./compiler/lua53.can:182
 return "table.unpack(" .. list .. (i and (", " .. i .. (j and (", " .. j) or "")) or "") .. ")" -- ./compiler/lua53.can:183
 end -- ./compiler/lua53.can:183
 local APPEND = function(t, toAppend) -- ./compiler/lua53.can:185
-return "do" .. indent() .. "local a = table.pack(" .. toAppend .. ")" .. newline() .. "table.move(a, 1, a.n, #" .. t .. "+1, " .. t .. ")" .. unindent() .. "end" -- ./compiler/lua53.can:186
+return "do" .. indent() .. "local " .. var("a") .. " = table.pack(" .. toAppend .. ")" .. newline() .. "table.move(" .. var("a") .. ", 1, " .. var("a") .. ".n, #" .. t .. "+1, " .. t .. ")" .. unindent() .. "end" -- ./compiler/lua53.can:186
 end -- ./compiler/lua53.can:186
 local CONTINUE_START = function() -- ./compiler/lua53.can:188
 return "do" .. indent() -- ./compiler/lua53.can:189
@@ -1155,7 +1155,7 @@ local UNPACK = function(list, i, j) -- ./compiler/lua53.can:182
 return "table.unpack(" .. list .. (i and (", " .. i .. (j and (", " .. j) or "")) or "") .. ")" -- ./compiler/lua53.can:183
 end -- ./compiler/lua53.can:183
 local APPEND = function(t, toAppend) -- ./compiler/lua53.can:185
-return "do" .. indent() .. "local a = table.pack(" .. toAppend .. ")" .. newline() .. "table.move(a, 1, a.n, #" .. t .. "+1, " .. t .. ")" .. unindent() .. "end" -- ./compiler/lua53.can:186
+return "do" .. indent() .. "local " .. var("a") .. " = table.pack(" .. toAppend .. ")" .. newline() .. "table.move(" .. var("a") .. ", 1, " .. var("a") .. ".n, #" .. t .. "+1, " .. t .. ")" .. unindent() .. "end" -- ./compiler/lua53.can:186
 end -- ./compiler/lua53.can:186
 local CONTINUE_START = function() -- ./compiler/lua53.can:188
 return "do" .. indent() -- ./compiler/lua53.can:189
@@ -1838,7 +1838,7 @@ UNPACK = function(list, i, j) -- ./compiler/luajit.can:3
 return "unpack(" .. list .. (i and (", " .. i .. (j and (", " .. j) or "")) or "") .. ")" -- ./compiler/luajit.can:4
 end -- ./compiler/luajit.can:4
 APPEND = function(t, toAppend) -- ./compiler/luajit.can:6
-return "do" .. indent() .. "local a, p = { " .. toAppend .. " }, #" .. t .. "+1" .. newline() .. "for i=1, #a do" .. indent() .. t .. "[p] = a[i]" .. newline() .. "p = p + 1" .. unindent() .. "end" .. unindent() .. "end" -- ./compiler/luajit.can:7
+return "do" .. indent() .. "local " .. var("a") .. ", " .. var("p") .. " = { " .. toAppend .. " }, #" .. t .. "+1" .. newline() .. "for i=1, #" .. var("a") .. " do" .. indent() .. t .. "[" .. var("p") .. "] = " .. var("a") .. "[i]" .. newline() .. "" .. var("p") .. " = " .. var("p") .. " + 1" .. unindent() .. "end" .. unindent() .. "end" -- ./compiler/luajit.can:7
 end -- ./compiler/luajit.can:7
 tags["_opid"]["idiv"] = function(left, right) -- ./compiler/luajit.can:10
 return "math.floor(" .. lua(left) .. " / " .. lua(right) .. ")" -- ./compiler/luajit.can:11
@@ -2049,7 +2049,7 @@ local UNPACK = function(list, i, j) -- ./compiler/lua53.can:182
 return "table.unpack(" .. list .. (i and (", " .. i .. (j and (", " .. j) or "")) or "") .. ")" -- ./compiler/lua53.can:183
 end -- ./compiler/lua53.can:183
 local APPEND = function(t, toAppend) -- ./compiler/lua53.can:185
-return "do" .. indent() .. "local a = table.pack(" .. toAppend .. ")" .. newline() .. "table.move(a, 1, a.n, #" .. t .. "+1, " .. t .. ")" .. unindent() .. "end" -- ./compiler/lua53.can:186
+return "do" .. indent() .. "local " .. var("a") .. " = table.pack(" .. toAppend .. ")" .. newline() .. "table.move(" .. var("a") .. ", 1, " .. var("a") .. ".n, #" .. t .. "+1, " .. t .. ")" .. unindent() .. "end" -- ./compiler/lua53.can:186
 end -- ./compiler/lua53.can:186
 local CONTINUE_START = function() -- ./compiler/lua53.can:188
 return "do" .. indent() -- ./compiler/lua53.can:189
@@ -2732,7 +2732,7 @@ UNPACK = function(list, i, j) -- ./compiler/luajit.can:3
 return "unpack(" .. list .. (i and (", " .. i .. (j and (", " .. j) or "")) or "") .. ")" -- ./compiler/luajit.can:4
 end -- ./compiler/luajit.can:4
 APPEND = function(t, toAppend) -- ./compiler/luajit.can:6
-return "do" .. indent() .. "local a, p = { " .. toAppend .. " }, #" .. t .. "+1" .. newline() .. "for i=1, #a do" .. indent() .. t .. "[p] = a[i]" .. newline() .. "p = p + 1" .. unindent() .. "end" .. unindent() .. "end" -- ./compiler/luajit.can:7
+return "do" .. indent() .. "local " .. var("a") .. ", " .. var("p") .. " = { " .. toAppend .. " }, #" .. t .. "+1" .. newline() .. "for i=1, #" .. var("a") .. " do" .. indent() .. t .. "[" .. var("p") .. "] = " .. var("a") .. "[i]" .. newline() .. "" .. var("p") .. " = " .. var("p") .. " + 1" .. unindent() .. "end" .. unindent() .. "end" -- ./compiler/luajit.can:7
 end -- ./compiler/luajit.can:7
 tags["_opid"]["idiv"] = function(left, right) -- ./compiler/luajit.can:10
 return "math.floor(" .. lua(left) .. " / " .. lua(right) .. ")" -- ./compiler/luajit.can:11
@@ -4485,7 +4485,7 @@ return parser -- ./candran/can-parser/parser.lua:744
 end -- ./candran/can-parser/parser.lua:744
 local parser = _() or parser -- ./candran/can-parser/parser.lua:748
 package["loaded"]["candran.can-parser.parser"] = parser or true -- ./candran/can-parser/parser.lua:749
-local candran = { ["VERSION"] = "0.11.0" } -- candran.can:14
+local candran = { ["VERSION"] = "0.12.0" } -- candran.can:14
 candran["default"] = { -- candran.can:18
 ["target"] = "lua53", -- candran.can:19
 ["indentation"] = "", -- candran.can:20
@@ -4503,212 +4503,228 @@ else -- candran.can:31
 candran["default"]["target"] = "lua51" -- candran.can:33
 end -- candran.can:33
 end -- candran.can:33
-candran["preprocess"] = function(input, options) -- candran.can:41
-if options == nil then options = {} end -- candran.can:41
-options = util["merge"](candran["default"], options) -- candran.can:42
-local preprocessor = "" -- candran.can:45
-local i = 0 -- candran.can:46
-local inLongString = false -- candran.can:47
-local inComment = false -- candran.can:48
+candran["preprocess"] = function(input, options) -- candran.can:43
+if options == nil then options = {} end -- candran.can:43
+options = util["merge"](candran["default"], options) -- candran.can:44
+local preprocessor = "" -- candran.can:47
+local i = 0 -- candran.can:48
+local inLongString = false -- candran.can:49
+local inComment = false -- candran.can:50
 for line in (input .. "\
 "):gmatch("(.-\
-)") do -- candran.can:49
-i = i + (1) -- candran.can:50
-if inComment then -- candran.can:52
-inComment = not line:match("%]%]") -- candran.can:53
-elseif inLongString then -- candran.can:54
-inLongString = not line:match("%]%]") -- candran.can:55
-else -- candran.can:55
-if line:match("[^%-]%[%[") then -- candran.can:57
-inLongString = true -- candran.can:58
-elseif line:match("%-%-%[%[") then -- candran.can:59
-inComment = true -- candran.can:60
-end -- candran.can:60
-end -- candran.can:60
-if not inComment and not inLongString and line:match("^%s*#") and not line:match("^#!") then -- candran.can:63
-preprocessor = preprocessor .. (line:gsub("^%s*#", "")) -- candran.can:64
-else -- candran.can:64
-local l = line:sub(1, - 2) -- candran.can:66
-if not inLongString and options["mapLines"] and not l:match("%-%- (.-)%:(%d+)$") then -- candran.can:67
+)") do -- candran.can:51
+i = i + (1) -- candran.can:52
+if inComment then -- candran.can:54
+inComment = not line:match("%]%]") -- candran.can:55
+elseif inLongString then -- candran.can:56
+inLongString = not line:match("%]%]") -- candran.can:57
+else -- candran.can:57
+if line:match("[^%-]%[%[") then -- candran.can:59
+inLongString = true -- candran.can:60
+elseif line:match("%-%-%[%[") then -- candran.can:61
+inComment = true -- candran.can:62
+end -- candran.can:62
+end -- candran.can:62
+if not inComment and not inLongString and line:match("^%s*#") and not line:match("^#!") then -- candran.can:65
+preprocessor = preprocessor .. (line:gsub("^%s*#", "")) -- candran.can:66
+else -- candran.can:66
+local l = line:sub(1, - 2) -- candran.can:68
+if not inLongString and options["mapLines"] and not l:match("%-%- (.-)%:(%d+)$") then -- candran.can:69
 preprocessor = preprocessor .. (("write(%q)"):format(l .. " -- " .. options["chunkname"] .. ":" .. i) .. "\
-") -- candran.can:68
-else -- candran.can:68
-preprocessor = preprocessor .. (("write(%q)"):format(line:sub(1, - 2)) .. "\
 ") -- candran.can:70
-end -- candran.can:70
-end -- candran.can:70
-end -- candran.can:70
-preprocessor = preprocessor .. ("return output") -- candran.can:74
-local env = util["merge"](_G, options) -- candran.can:77
-env["candran"] = candran -- candran.can:79
-env["output"] = "" -- candran.can:81
-env["import"] = function(modpath, margs) -- candran.can:88
-if margs == nil then margs = {} end -- candran.can:88
-local filepath = assert(util["search"](modpath, { -- candran.can:89
-"can", -- candran.can:89
-"lua" -- candran.can:89
-}), "No module named \"" .. modpath .. "\"") -- candran.can:89
-local f = io["open"](filepath) -- candran.can:92
-if not f then -- candran.can:93
-error("Can't open the module file to import") -- candran.can:93
-end -- candran.can:93
-margs = util["merge"](options, { -- candran.can:95
-["chunkname"] = filepath, -- candran.can:95
-["loadLocal"] = true, -- candran.can:95
-["loadPackage"] = true -- candran.can:95
-}, margs) -- candran.can:95
-local modcontent = candran["preprocess"](f:read("*a"), margs) -- candran.can:96
-f:close() -- candran.can:97
-local modname = modpath:match("[^%.]+$") -- candran.can:100
+else -- candran.can:70
+preprocessor = preprocessor .. (("write(%q)"):format(line:sub(1, - 2)) .. "\
+") -- candran.can:72
+end -- candran.can:72
+end -- candran.can:72
+end -- candran.can:72
+preprocessor = preprocessor .. ("return output") -- candran.can:76
+local env = util["merge"](_G, options) -- candran.can:79
+env["candran"] = candran -- candran.can:81
+env["output"] = "" -- candran.can:83
+env["import"] = function(modpath, margs) -- candran.can:90
+if margs == nil then margs = {} end -- candran.can:90
+local filepath = assert(util["search"](modpath, { -- candran.can:91
+"can", -- candran.can:91
+"lua" -- candran.can:91
+}), "No module named \"" .. modpath .. "\"") -- candran.can:91
+local f = io["open"](filepath) -- candran.can:94
+if not f then -- candran.can:95
+error("can't open the module file to import") -- candran.can:95
+end -- candran.can:95
+margs = util["merge"](options, { -- candran.can:97
+["chunkname"] = filepath, -- candran.can:97
+["loadLocal"] = true, -- candran.can:97
+["loadPackage"] = true -- candran.can:97
+}, margs) -- candran.can:97
+local modcontent = assert(candran["preprocess"](f:read("*a"), margs)) -- candran.can:98
+f:close() -- candran.can:99
+local modname = modpath:match("[^%.]+$") -- candran.can:102
 env["write"]("-- MODULE " .. modpath .. " --\
 " .. "local function _()\
 " .. modcontent .. "\
 " .. "end\
 " .. (margs["loadLocal"] and ("local %s = _() or %s\
 "):format(modname, modname) or "") .. (margs["loadPackage"] and ("package.loaded[%q] = %s or true\
-"):format(modpath, margs["loadLocal"] and modname or "_()") or "") .. "-- END OF MODULE " .. modpath .. " --") -- candran.can:109
-end -- candran.can:109
-env["include"] = function(file) -- candran.can:114
-local f = io["open"](file) -- candran.can:115
-if not f then -- candran.can:116
-error("Can't open the file " .. file .. " to include") -- candran.can:116
-end -- candran.can:116
-env["write"](f:read("*a")) -- candran.can:117
-f:close() -- candran.can:118
+"):format(modpath, margs["loadLocal"] and modname or "_()") or "") .. "-- END OF MODULE " .. modpath .. " --") -- candran.can:111
+end -- candran.can:111
+env["include"] = function(file) -- candran.can:116
+local f = io["open"](file) -- candran.can:117
+if not f then -- candran.can:118
+error("can't open the file " .. file .. " to include") -- candran.can:118
 end -- candran.can:118
-env["write"] = function(...) -- candran.can:122
+env["write"](f:read("*a")) -- candran.can:119
+f:close() -- candran.can:120
+end -- candran.can:120
+env["write"] = function(...) -- candran.can:124
 env["output"] = env["output"] .. (table["concat"]({ ... }, "\9") .. "\
-") -- candran.can:123
-end -- candran.can:123
-env["placeholder"] = function(name) -- candran.can:127
-if env[name] then -- candran.can:128
-env["write"](env[name]) -- candran.can:129
-end -- candran.can:129
-end -- candran.can:129
-local preprocess, err = util["load"](candran["compile"](preprocessor, args), "candran preprocessor", env) -- candran.can:134
-if not preprocess then -- candran.can:135
-error("Error while creating Candran preprocessor: " .. err) -- candran.can:135
-end -- candran.can:135
-local success, output = pcall(preprocess) -- candran.can:138
-if not success then -- candran.can:139
-error("Error while preprocessing file: " .. output) -- candran.can:139
-end -- candran.can:139
-return output -- candran.can:141
-end -- candran.can:141
-candran["compile"] = function(input, options) -- candran.can:148
-if options == nil then options = {} end -- candran.can:148
-options = util["merge"](candran["default"], options) -- candran.can:149
-local ast, errmsg = parser["parse"](input, options["chunkname"]) -- candran.can:151
-if not ast then -- candran.can:153
-error("Compiler: error while parsing file: " .. errmsg) -- candran.can:154
-end -- candran.can:154
-return require("compiler." .. options["target"])(input, ast, options) -- candran.can:157
-end -- candran.can:157
-candran["make"] = function(code, options) -- candran.can:164
-return candran["compile"](candran["preprocess"](code, options), options) -- candran.can:165
-end -- candran.can:165
-local errorRewritingActive = false -- candran.can:168
-local codeCache = {} -- candran.can:169
-candran["loadfile"] = function(filepath, env, options) -- candran.can:172
-local f, err = io["open"](filepath) -- candran.can:173
-if not f then -- candran.can:174
-error("can't open the file: " .. err) -- candran.can:174
-end -- candran.can:174
-local content = f:read("*a") -- candran.can:175
-f:close() -- candran.can:176
-return candran["load"](content, filepath, env, options) -- candran.can:178
-end -- candran.can:178
-candran["load"] = function(chunk, chunkname, env, options) -- candran.can:183
-if options == nil then options = {} end -- candran.can:183
-options = util["merge"]({ ["chunkname"] = tostring(chunkname or chunk) }, options) -- candran.can:184
-codeCache[options["chunkname"]] = candran["make"](chunk, options) -- candran.can:186
-local f, err = util["load"](codeCache[options["chunkname"]], options["chunkname"], env) -- candran.can:187
-if f == nil then -- candran.can:192
-return f, "Candran unexpectedly generated invalid code: " .. err -- candran.can:193
-end -- candran.can:193
-if options["rewriteErrors"] == false then -- candran.can:196
-return f -- candran.can:197
-else -- candran.can:197
-return function(...) -- candran.can:199
-local params = { ... } -- candran.can:200
-if not errorRewritingActive then -- candran.can:201
-errorRewritingActive = true -- candran.can:202
-local t = { xpcall(function() -- candran.can:203
-return f(unpack(params)) -- candran.can:203
-end, candran["messageHandler"]) } -- candran.can:203
-errorRewritingActive = false -- candran.can:204
-if t[1] == false then -- candran.can:205
-error(t[2], 0) -- candran.can:206
-end -- candran.can:206
-return unpack(t, 2) -- candran.can:208
-else -- candran.can:208
-return f(...) -- candran.can:210
-end -- candran.can:210
-end -- candran.can:210
-end -- candran.can:210
-end -- candran.can:210
-candran["dofile"] = function(filename, options) -- candran.can:218
-local f, err = candran["loadfile"](filename, nil, options) -- candran.can:219
+") -- candran.can:125
+end -- candran.can:125
+env["placeholder"] = function(name) -- candran.can:129
+if env[name] then -- candran.can:130
+env["write"](env[name]) -- candran.can:131
+end -- candran.can:131
+end -- candran.can:131
+local preprocess, err = candran["compile"](preprocessor, options) -- candran.can:136
+if not preprocess then -- candran.can:137
+return nil, "in preprocessor: " .. err -- candran.can:138
+end -- candran.can:138
+preprocess, err = util["load"](preprocessor, "candran preprocessor", env) -- candran.can:141
+if not preprocess then -- candran.can:142
+return nil, "in preprocessor: " .. err -- candran.can:143
+end -- candran.can:143
+local success, output = pcall(preprocess) -- candran.can:147
+if not success then -- candran.can:148
+return nil, "in preprocessor: " .. output -- candran.can:149
+end -- candran.can:149
+return output -- candran.can:152
+end -- candran.can:152
+candran["compile"] = function(input, options) -- candran.can:161
+if options == nil then options = {} end -- candran.can:161
+options = util["merge"](candran["default"], options) -- candran.can:162
+local ast, errmsg = parser["parse"](input, options["chunkname"]) -- candran.can:164
+if not ast then -- candran.can:166
+return nil, errmsg -- candran.can:167
+end -- candran.can:167
+return require("compiler." .. options["target"])(input, ast, options) -- candran.can:170
+end -- candran.can:170
+candran["make"] = function(code, options) -- candran.can:179
+local r, err = candran["preprocess"](code, options) -- candran.can:180
+if r then -- candran.can:181
+r, err = candran["compile"](r, options) -- candran.can:182
+if r then -- candran.can:183
+return r -- candran.can:184
+end -- candran.can:184
+end -- candran.can:184
+return r, err -- candran.can:187
+end -- candran.can:187
+local errorRewritingActive = false -- candran.can:190
+local codeCache = {} -- candran.can:191
+candran["loadfile"] = function(filepath, env, options) -- candran.can:194
+local f, err = io["open"](filepath) -- candran.can:195
+if not f then -- candran.can:196
+return nil, ("cannot open %s"):format(err) -- candran.can:197
+end -- candran.can:197
+local content = f:read("*a") -- candran.can:199
+f:close() -- candran.can:200
+return candran["load"](content, filepath, env, options) -- candran.can:202
+end -- candran.can:202
+candran["load"] = function(chunk, chunkname, env, options) -- candran.can:207
+if options == nil then options = {} end -- candran.can:207
+options = util["merge"]({ ["chunkname"] = tostring(chunkname or chunk) }, options) -- candran.can:208
+local code, err = candran["make"](chunk, options) -- candran.can:210
+if not code then -- candran.can:211
+return code, err -- candran.can:212
+end -- candran.can:212
+codeCache[options["chunkname"]] = code -- candran.can:215
+local f, err = util["load"](code, options["chunkname"], env) -- candran.can:216
 if f == nil then -- candran.can:221
-error(err) -- candran.can:222
-else -- candran.can:222
-return f() -- candran.can:224
-end -- candran.can:224
-end -- candran.can:224
-candran["messageHandler"] = function(message) -- candran.can:230
+return f, "candran unexpectedly generated invalid code: " .. err -- candran.can:222
+end -- candran.can:222
+if options["rewriteErrors"] == false then -- candran.can:225
+return f -- candran.can:226
+else -- candran.can:226
+return function(...) -- candran.can:228
+local params = { ... } -- candran.can:229
+if not errorRewritingActive then -- candran.can:230
+errorRewritingActive = true -- candran.can:231
+local t = { xpcall(function() -- candran.can:232
+return f(unpack(params)) -- candran.can:232
+end, candran["messageHandler"]) } -- candran.can:232
+errorRewritingActive = false -- candran.can:233
+if t[1] == false then -- candran.can:234
+error(t[2], 0) -- candran.can:235
+end -- candran.can:235
+return unpack(t, 2) -- candran.can:237
+else -- candran.can:237
+return f(...) -- candran.can:239
+end -- candran.can:239
+end -- candran.can:239
+end -- candran.can:239
+end -- candran.can:239
+candran["dofile"] = function(filename, options) -- candran.can:247
+local f, err = candran["loadfile"](filename, nil, options) -- candran.can:248
+if f == nil then -- candran.can:250
+error(err) -- candran.can:251
+else -- candran.can:251
+return f() -- candran.can:253
+end -- candran.can:253
+end -- candran.can:253
+candran["messageHandler"] = function(message) -- candran.can:259
 return debug["traceback"](message, 2):gsub("(\
 ?%s*)([^\
-]-)%:(%d+)%:", function(indentation, source, line) -- candran.can:231
-line = tonumber(line) -- candran.can:232
-local originalFile -- candran.can:234
-local strName = source:match("%[string \"(.-)\"%]") -- candran.can:235
-if strName then -- candran.can:236
-if codeCache[strName] then -- candran.can:237
-originalFile = codeCache[strName] -- candran.can:238
-source = strName -- candran.can:239
-end -- candran.can:239
-else -- candran.can:239
-local fi = io["open"](source, "r") -- candran.can:242
-if fi then -- candran.can:243
-originalFile = fi:read("*a") -- candran.can:244
-fi:close() -- candran.can:245
-end -- candran.can:245
-end -- candran.can:245
-if originalFile then -- candran.can:249
-local i = 0 -- candran.can:250
-for l in originalFile:gmatch("([^\
+]-)%:(%d+)%:", function(indentation, source, line) -- candran.can:260
+line = tonumber(line) -- candran.can:261
+local originalFile -- candran.can:263
+local strName = source:match("%[string \"(.-)\"%]") -- candran.can:264
+if strName then -- candran.can:265
+if codeCache[strName] then -- candran.can:266
+originalFile = codeCache[strName] -- candran.can:267
+source = strName -- candran.can:268
+end -- candran.can:268
+else -- candran.can:268
+local fi = io["open"](source, "r") -- candran.can:271
+if fi then -- candran.can:272
+originalFile = fi:read("*a") -- candran.can:273
+fi:close() -- candran.can:274
+end -- candran.can:274
+end -- candran.can:274
+if originalFile then -- candran.can:278
+local i = 0 -- candran.can:279
+for l in (originalFile .. "\
+"):gmatch("([^\
 ]*)\
-") do -- candran.can:251
-i = i + 1 -- candran.can:252
-if i == line then -- candran.can:253
-local extSource, lineMap = l:match(".*%-%- (.-)%:(%d+)$") -- candran.can:254
-if lineMap then -- candran.can:255
-if extSource ~= source then -- candran.can:256
-return indentation .. extSource .. ":" .. lineMap .. "(" .. extSource .. ":" .. line .. "):" -- candran.can:257
-else -- candran.can:257
-return indentation .. extSource .. ":" .. lineMap .. "(" .. line .. "):" -- candran.can:259
-end -- candran.can:259
-end -- candran.can:259
-break -- candran.can:262
-end -- candran.can:262
-end -- candran.can:262
-end -- candran.can:262
-end) -- candran.can:262
-end -- candran.can:262
-candran["searcher"] = function(modpath) -- candran.can:270
-local filepath = util["search"](modpath, { "can" }) -- candran.can:271
-if not filepath then -- candran.can:272
+") do -- candran.can:280
+i = i + 1 -- candran.can:281
+if i == line then -- candran.can:282
+local extSource, lineMap = l:match(".*%-%- (.-)%:(%d+)$") -- candran.can:283
+if lineMap then -- candran.can:284
+if extSource ~= source then -- candran.can:285
+return indentation .. extSource .. ":" .. lineMap .. "(" .. extSource .. ":" .. line .. "):" -- candran.can:286
+else -- candran.can:286
+return indentation .. extSource .. ":" .. lineMap .. "(" .. line .. "):" -- candran.can:288
+end -- candran.can:288
+end -- candran.can:288
+break -- candran.can:291
+end -- candran.can:291
+end -- candran.can:291
+end -- candran.can:291
+end) -- candran.can:291
+end -- candran.can:291
+candran["searcher"] = function(modpath) -- candran.can:299
+local filepath = util["search"](modpath, { "can" }) -- candran.can:300
+if not filepath then -- candran.can:301
 return "\
-\9no candran file in package.path" -- candran.can:273
-end -- candran.can:273
-return candran["loadfile"](filepath) -- candran.can:275
-end -- candran.can:275
-candran["setup"] = function() -- candran.can:279
-if _VERSION == "Lua 5.1" then -- candran.can:280
-table["insert"](package["loaders"], 2, candran["searcher"]) -- candran.can:281
-else -- candran.can:281
-table["insert"](package["searchers"], 2, candran["searcher"]) -- candran.can:283
-end -- candran.can:283
-return candran -- candran.can:285
-end -- candran.can:285
-return candran -- candran.can:288
+\9no candran file in package.path" -- candran.can:302
+end -- candran.can:302
+return candran["loadfile"](filepath) -- candran.can:304
+end -- candran.can:304
+candran["setup"] = function() -- candran.can:308
+if _VERSION == "Lua 5.1" then -- candran.can:309
+table["insert"](package["loaders"], 2, candran["searcher"]) -- candran.can:310
+else -- candran.can:310
+table["insert"](package["searchers"], 2, candran["searcher"]) -- candran.can:312
+end -- candran.can:312
+return candran -- candran.can:314
+end -- candran.can:314
+return candran -- candran.can:317
diff --git a/compiler/lua53.can b/compiler/lua53.can
index 7e390df..5dabc03 100644
--- a/compiler/lua53.can
+++ b/compiler/lua53.can
@@ -183,7 +183,7 @@ return function(code, ast, options)
 		return "table.unpack("..list..(i and (", "..i..(j and (", "..j) or "")) or "")..")"
 	end
 	local APPEND = (t, toAppend) -- append values "toAppend" (multiple values possible) to t
-		return "do"..indent().."local a = table.pack("..toAppend..")"..newline().."table.move(a, 1, a.n, #"..t.."+1, "..t..")"..unindent().."end"
+		return "do"..indent().."local "..var("a").." = table.pack("..toAppend..")"..newline().."table.move("..var("a")..", 1, "..var("a")..".n, #"..t.."+1, "..t..")"..unindent().."end"
 	end
 	local CONTINUE_START = () -- at the start of loops using continue
 		return "do"..indent()
diff --git a/compiler/luajit.can b/compiler/luajit.can
index a4d068b..9428fc5 100644
--- a/compiler/luajit.can
+++ b/compiler/luajit.can
@@ -4,7 +4,7 @@ UNPACK = (list, i, j)
 	return "unpack(" .. list .. (i and (", " .. i .. (j and (", " .. j) or "")) or "") .. ")"
 end
 APPEND = (t, toAppend)
-	return "do" .. indent() .. "local a, p = { " .. toAppend .. " }, #" .. t .. "+1" .. newline() .. "for i=1, #a do" .. indent() .. t .. "[p] = a[i]" .. newline() .. "p = p + 1" .. unindent() .. "end" .. unindent() .. "end"
+	return "do" .. indent() .. "local "..var("a")..", "..var("p").." = { " .. toAppend .. " }, #" .. t .. "+1" .. newline() .. "for i=1, #"..var("a").." do" .. indent() .. t .. "["..var("p").."] = "..var("a").."[i]" .. newline() .. ""..var("p").." = "..var("p").." + 1" .. unindent() .. "end" .. unindent() .. "end"
 end
 
 tags._opid.idiv = (left, right)
diff --git a/rockspec/candran-scm-1.rockspec b/rockspec/candran-scm-1.rockspec
index f12891e..c6573dd 100644
--- a/rockspec/candran-scm-1.rockspec
+++ b/rockspec/candran-scm-1.rockspec
@@ -23,7 +23,9 @@ source = {
 
 dependencies = {
 	"lua >= 5.1",
-	"lpeglabel >= 1.5.0"
+	"lpeglabel >= 1.5.0",
+	"linenoise >= 0.9",
+	"luacheck >= 0.23.0"
 }
 
 build = {
@@ -32,6 +34,6 @@ build = {
 		candran = "candran.lua"
 	},
 	install = {
-		bin = { "bin/can", "bin/canc" }
+		bin = { "bin/can", "bin/canc", "bin/cancheck" }
 	}
 }
diff --git a/test/test.lua b/test/test.lua
index 1588ab0..62ef409 100644
--- a/test/test.lua
+++ b/test/test.lua
@@ -15,7 +15,7 @@ local function test(name, candranCode, expectedResult, options)
 	options.chunkname = name
 
 	-- make code
-	local success, code = pcall(candran.make, candranCode, options)
+	local success, code = pcall(function() return assert(candran.make(candranCode, options)) end)
 	if not success then
 		self.result = "error"
 		self.message = "/!\\ error while making code:\n"..code