Move Mime(Un)Render and remove types which don't have instances for them

servant.cabal

@@ -45,6 +45,7 @@ library
     Servant.Utils.Links
   build-depends:
       base >=4.7 && <5
+    , aeson >= 0.7
     , bytestring == 0.10.*
     , http-media >= 0.4 && < 0.6
     , http-types == 0.8.*

src/Servant/API.hs

@@ -46,9 +46,8 @@ module Servant.API (
 
 import Servant.API.Alternative ( (:<|>)(..) )
 import Servant.API.Capture ( Capture )
-import Servant.API.ContentTypes ( HTML, XML, JSON, JavaScript, CSS
+import Servant.API.ContentTypes ( JSON , PlainText, OctetStream
-                                , PlainText, OctetStream, MimeRender(..)
+                                , MimeRender(..) , MimeUnrender(..))
-                                , MimeUnrender(..))
 import Servant.API.Delete ( Delete )
 import Servant.API.Get ( Get )
 import Servant.API.Header ( Header )

src/Servant/API/ContentTypes.hs

@@ -1,6 +1,6 @@
-{-# LANGUAGE DeriveDataTypeable #-}
-{-# LANGUAGE DataKinds #-}
 {-# LANGUAGE ConstraintKinds       #-}
+{-# LANGUAGE DataKinds             #-}
+{-# LANGUAGE DeriveDataTypeable    #-}
 {-# LANGUAGE FlexibleInstances     #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE OverloadedStrings     #-}
@@ -11,19 +11,20 @@
 {-# LANGUAGE UndecidableInstances  #-}
 module Servant.API.ContentTypes where
 
+import           Control.Arrow           (left)
+import           Data.Aeson              (FromJSON, ToJSON, eitherDecode,
+                                          encode)
 import qualified Data.ByteString         as BS
 import           Data.ByteString.Lazy    (ByteString)
 import           Data.String.Conversions (cs)
+import qualified Data.Text.Lazy          as Text
+import qualified Data.Text.Lazy.Encoding as Text
 import           Data.Typeable
 import           GHC.Exts                (Constraint)
 import qualified Network.HTTP.Media      as M
 
 -- * Provided content types
-data XML deriving Typeable
-data HTML deriving Typeable
 data JSON deriving Typeable
-data JavaScript deriving Typeable
-data CSS deriving Typeable
 data PlainText deriving Typeable
 data OctetStream deriving Typeable
 
@@ -41,26 +42,10 @@ data OctetStream deriving Typeable
 class Accept ctype where
     contentType   :: Proxy ctype -> M.MediaType
 
--- | @text/html;charset=utf-8@
-instance Accept HTML where
-    contentType _ = "text" M.// "html" M./: ("charset", "utf-8")
-
 -- | @application/json;charset=utf-8@
 instance Accept JSON where
     contentType _ = "application" M.// "json" M./: ("charset", "utf-8")
 
--- | @application/xml;charset=utf-8@
-instance Accept XML where
-    contentType _ = "application" M.// "xml" M./: ("charset", "utf-8")
-
--- | @application/javascript;charset=utf-8@
-instance Accept JavaScript where
-    contentType _ = "application" M.// "javascript" M./: ("charset", "utf-8")
-
--- | @text/css;charset=utf-8@
-instance Accept CSS where
-    contentType _ = "text" M.// "css" M./: ("charset", "utf-8")
-
 -- | @text/plain;charset=utf-8@
 instance Accept PlainText where
     contentType _ = "text" M.// "plain" M./: ("charset", "utf-8")
@@ -168,3 +153,34 @@ instance ( MimeUnrender ctyp a
 
 type family IsNonEmpty (ls::[*]) :: Constraint where
     IsNonEmpty (x ': xs)   = ()
+
+
+--------------------------------------------------------------------------
+-- * MimeRender Instances
+
+-- | `encode`
+instance ToJSON a => MimeRender JSON a where
+    toByteString _ = encode
+
+-- | `Text.encodeUtf8`
+instance MimeRender PlainText Text.Text where
+    toByteString _ = Text.encodeUtf8
+
+-- | `id`
+instance MimeRender OctetStream ByteString where
+    toByteString _ = id
+
+--------------------------------------------------------------------------
+-- * MimeUnrender Instances
+
+-- | `eitherDecode`
+instance FromJSON a => MimeUnrender JSON a where
+    fromByteString _ = eitherDecode
+
+-- | `left show . Text.decodeUtf8'`
+instance MimeUnrender PlainText Text.Text where
+    fromByteString _ = left show . Text.decodeUtf8'
+
+-- | `Right . id`
+instance MimeUnrender OctetStream ByteString where
+    fromByteString _ = Right . id

test/Servant/Utils/LinksSpec.hs

@@ -29,15 +29,15 @@ type TestApi =
   :<|> "raw" :> Raw
 
 type TestLink = "hello" :> "hi" :> Get '[JSON] Bool
-type TestLink2 = "greet" :> Post '[XML] Bool
+type TestLink2 = "greet" :> Post '[PlainText] Bool
 type TestLink3 = "parent" :> "child" :> Get '[JSON] String
 
 type BadTestLink = "hallo" :> "hi" :> Get '[JSON] Bool
-type BadTestLink2 = "greet" :> Get '[XML] Bool
+type BadTestLink2 = "greet" :> Get '[PlainText] Bool
 type BadTestLink3 = "parent" :> "child" :> MatrixFlag "male" :> Get '[JSON] String
 
-type BadTestLink' = "hello" :> "hi" :> Get '[HTML] Bool
+type BadTestLink' = "hello" :> "hi" :> Get '[OctetStream] Bool
-type BadTestLink'2 = "greet" :> Get '[HTML] Bool
+type BadTestLink'2 = "greet" :> Get '[OctetStream] Bool
 
 type NotALink = "hello" :> Capture "x" Bool :> Get '[JSON] Bool
 type NotALink2 = "hello" :> ReqBody '[JSON] 'True :> Get '[JSON] Bool