yesod/Yesod/Definitions.hs

58 lines
1.7 KiB
Haskell

{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE TypeSynonymInstances #-}
{-# LANGUAGE DeriveDataTypeable #-}
---------------------------------------------------------
--
-- Module : Yesod.Definitions
-- Copyright : Michael Snoyman
-- License : BSD3
--
-- Maintainer : Michael Snoyman <michael@snoyman.com>
-- Stability : Stable
-- Portability : portable
--
-- Definitions throughout Restful.
--
---------------------------------------------------------
module Yesod.Definitions
( Verb (..)
, Resource
, Approot (..)
, Language
) where
import qualified Hack
import Data.Convertible.Text
import Control.Exception (Exception)
import Data.Typeable (Typeable)
import Language.Haskell.TH.Syntax
data Verb = Get | Put | Delete | Post
deriving (Eq, Show, Enum, Bounded)
instance Lift Verb where
lift = return . ConE . mkName . show
instance ConvertAttempt String Verb where
convertAttempt "Get" = return Get
convertAttempt "Put" = return Put
convertAttempt "Delete" = return Delete
convertAttempt "Post" = return Post
convertAttempt s = failure $ InvalidVerb s
newtype InvalidVerb = InvalidVerb String
deriving (Show, Typeable)
instance Exception InvalidVerb
instance ConvertSuccess Hack.RequestMethod Verb where
convertSuccess Hack.PUT = Put
convertSuccess Hack.DELETE = Delete
convertSuccess Hack.POST = Post
convertSuccess _ = Get
type Resource = [String]
-- | An absolute URL to the base of this application. This can almost be done
-- programatically, but due to ambiguities in different ways of doing URL
-- rewriting for (fast)cgi applications, it should be supplied by the user.
newtype Approot = Approot { unApproot :: String }
type Language = String