Change API to use success,result return for loaders

.editorconfig

@@ -0,0 +1,2 @@
+[*]
+indent_style = tab

.luarc.json

@@ -0,0 +1,3 @@
+{
+    "workspace.checkThirdParty": false
+}

glass.lua

@@ -21,8 +21,8 @@ function __metatable:__index(index)
 		return config.bind(path, self.__loaders)
 	else
 		for _, loader in ipairs(self.__loaders) do
-			local result = loader(path)
-			if result then
+			local success, result = loader(path)
+			if success then
 				rawset(self, index, result)
 				return result
 			end

glass/cosmo.lua

@@ -12,8 +12,6 @@ return function(name)
 	name = tostring(name) .. '.cosmo'
 	local text = raw(name)
 	if text then
-		return assert(cosmo.compile(text, name))
-	else
-		return nil
+		return true, assert(cosmo.compile(text, name))
 	end
 end

glass/csv.lua

@@ -10,6 +10,6 @@ local csv = require 'streamcsv'
 return function(name)
 	local file = io.open(name..'.csv')
 	if file then
-		return csv.file(file)
+		return true, csv.file(file)
 	end
 end

glass/discount.lua

@@ -14,10 +14,8 @@ return function(name)
 	local file = io.open(name)
 	if file then
 		local html = discount(file:read("*a"))
-		return function()
+		return true, function()
 			return html
 		end
-	else
-		return nil
 	end
 end

glass/environment.lua

@@ -4,5 +4,5 @@
 --- Loads values from environment variables
 -- @treturn string The value of the environment variable
 return function(name)
-	return os.getenv(name:match("[^/].+$"))
+	return true, os.getenv(name:match("[^/].+$"))
 end

glass/json.lua

@@ -11,8 +11,8 @@ local read = require 'glass.raw'
 -- @treturn table JSON-Data
 -- @function load
 return function(file)
-	local raw = read(file..'.json')
-	if raw then
-		return json.decode(raw)
+	local success, raw = read(file..'.json')
+	if success then
+		return true, json.decode(raw)
 	end
 end

glass/lua.lua

@@ -9,5 +9,7 @@
 -- @function load
 return function(name)
 	local f = loadfile(name..'.lua')
-	return f and f() or nil
+	if f then
+		return true, f()
+	end
 end

glass/moonhtml.lua

@@ -1,7 +1,6 @@
 --- Loader for MoonHTML files
 -- @module glass.moonhtml
 
-
 local template = require 'restia.template'
 
 --- Loads and compiles a moonhtml template.
@@ -11,7 +10,7 @@ return function(name)
 	name = tostring(name) .. '.moonhtml'
 	local file = io.open(name)
 	if file then
-		return assert(template.loadmoon(file:read("*a"), name))
+		return true, assert(template.loadmoon(file:read("*a"), name))
 	else
 		return nil
 	end

glass/raw.lua

@@ -6,8 +6,10 @@
 -- @function load
 return function(path)
 	local f = io.open(path)
-	if not f then return end
+	if not f then
+		return false
+	end
 	local result = f:read("*a")
 	f:close()
-	return result
+	return true, result
 end

glass/skooma/html.lua

@@ -24,5 +24,5 @@ return function(name)
 	if setfenv then
 		setfenv(template, env)
 	end
-	return template
+	return true, template
 end

glass/skooma/xml.lua

@@ -24,5 +24,5 @@ return function(name)
 	if setfenv then
 		setfenv(template, env)
 	end
-	return template
+	return true, template
 end

glass/table.lua

@@ -7,6 +7,9 @@
 -- @treturn function A loader function to be used with `glass.bind`
 return function(input)
 	return function(name)
-		return input[name:match("[^/].+$")]
+		local result = input[name:match("[^/].+$")]
+		if result then
+			return true, result
+		end
 	end
 end

glass/yaml.lua

@@ -11,8 +11,11 @@ local read = require 'glass.raw'
 -- @treturn table YAML-Data
 -- @function load
 return function(file)
-	local raw = read(file..'.yml') or read(file..'.yaml')
-	if raw then
-		return yaml.load(raw)
+	local success, raw = read(file..'.yml')
+	if not success then
+		success, raw = read(file..'.yaml')
+	end
+	if success then
+		return true, yaml.load(raw)
 	end
 end

spec/loaders_spec.moon

@@ -1,9 +1,11 @@
 describe 'raw loader', ->
 	before_each -> export loader = require 'glass.raw'
 	it 'loads files as plain text', ->
-		assert.same 'plain text\n', loader 'spec/fixtures/test'
+		assert.same {true, 'plain text\n'}, {loader 'spec/fixtures/test'}
 
 describe 'lua loader', ->
 	before_each -> export loader = require 'glass.lua'
 	it 'loads Lua files', ->
-		assert.same { foo: 'bar', tab: {} }, loader 'spec/fixtures/test'
+		success, result = loader 'spec/fixtures/test'
+		assert.true success
+		assert.same { foo: 'bar', tab: {} }, result