diff --git a/servant-foreign/servant-foreign.cabal b/servant-foreign/servant-foreign.cabal
index 2dc94cac..ebeb3dfe 100644
--- a/servant-foreign/servant-foreign.cabal
+++ b/servant-foreign/servant-foreign.cabal
@@ -25,7 +25,7 @@ source-repository head
   location: http://github.com/haskell-servant/servant.git
 
 library
-  exposed-modules:     Servant.Foreign
+  exposed-modules:     Servant.Foreign, Servant.Foreign.Internal
   build-depends:       base    == 4.*
                      , lens    == 4.*
                      , servant == 0.5.*
diff --git a/servant-foreign/src/Servant/Foreign.hs b/servant-foreign/src/Servant/Foreign.hs
index f4582c22..3baa9887 100644
--- a/servant-foreign/src/Servant/Foreign.hs
+++ b/servant-foreign/src/Servant/Foreign.hs
@@ -1,19 +1,3 @@
-{-# LANGUAGE CPP                   #-}
-{-# LANGUAGE ConstraintKinds       #-}
-{-# LANGUAGE DataKinds             #-}
-{-# LANGUAGE FlexibleContexts      #-}
-{-# LANGUAGE FlexibleInstances     #-}
-#if !MIN_VERSION_base(4,8,0)
-{-# LANGUAGE NullaryTypeClasses    #-}
-#endif
-{-# LANGUAGE MultiParamTypeClasses #-}
-{-# LANGUAGE ScopedTypeVariables   #-}
-{-# LANGUAGE TemplateHaskell       #-}
-{-# LANGUAGE TypeFamilies          #-}
-{-# LANGUAGE TypeOperators         #-}
-{-# LANGUAGE UndecidableInstances  #-}
-{-# LANGUAGE OverloadedStrings     #-}
-
 -- | Generalizes all the data needed to make code generation work with
 -- arbitrary programming languages.
 module Servant.Foreign
@@ -46,244 +30,5 @@ module Servant.Foreign
   , module Servant.API
   ) where
 
-import           Control.Lens (makeLenses, (%~), (&), (.~), (<>~))
-import qualified Data.Char    as C
-import           Data.Proxy
-import           Data.Text
-import           GHC.Exts     (Constraint)
-import           GHC.TypeLits
-import           Prelude      hiding (concat)
-import           Servant.API
-
--- | Function name builder that simply concat each part together
-concatCase :: FunctionName -> Text
-concatCase = concat
-
--- | Function name builder using the snake_case convention.
--- each part is separated by a single underscore character.
-snakeCase :: FunctionName -> Text
-snakeCase = intercalate "_"
-
--- | Function name builder using the CamelCase convention.
--- each part begins with an upper case character.
-camelCase :: FunctionName -> Text
-camelCase = camelCase' . Prelude.map (replace "-" "")
-  where camelCase' []     = ""
-        camelCase' (p:ps) = concat $ p : Prelude.map capitalize ps
-        capitalize ""   = ""
-        capitalize name = C.toUpper (Data.Text.head name) `cons` Data.Text.tail name
-
-type Arg = Text
-
-newtype Segment = Segment { _segment :: SegmentType  }
-  deriving (Eq, Show)
-
-data SegmentType = Static Text  -- ^ a static path segment. like "/foo"
-                 | Cap Arg        -- ^ a capture. like "/:userid"
-  deriving (Eq, Show)
-
-type Path = [Segment]
-
-data ArgType =
-    Normal
-  | Flag
-  | List
-  deriving (Eq, Show)
-
-data QueryArg = QueryArg
-  { _argName :: Arg
-  , _argType :: ArgType
-  } deriving (Eq, Show)
-
-data HeaderArg = HeaderArg
-    { headerArgName :: Text
-    }
-  | ReplaceHeaderArg
-    { headerArgName :: Text
-    , headerPattern :: Text
-    } deriving (Eq, Show)
-
-
-data Url = Url
-  { _path     :: Path
-  , _queryStr :: [QueryArg]
-  } deriving (Eq, Show)
-
-defUrl :: Url
-defUrl = Url [] []
-
-type FunctionName = [Text]
-type Method = Text
-
-data Req = Req
-  { _reqUrl     :: Url
-  , _reqMethod  :: Method
-  , _reqHeaders :: [HeaderArg]
-  , _reqBody    :: Bool
-  , _funcName   :: FunctionName
-  } deriving (Eq, Show)
-
-makeLenses ''QueryArg
-makeLenses ''Segment
-makeLenses ''Url
-makeLenses ''Req
-
-isCapture :: Segment -> Bool
-isCapture (Segment (Cap _)) = True
-isCapture                _  = False
-
-captureArg :: Segment -> Arg
-captureArg (Segment (Cap s)) = s
-captureArg                 _ = error "captureArg called on non capture"
-
-defReq :: Req
-defReq = Req defUrl "GET" [] False []
-
--- | To be used exclusively as a "negative" return type/constraint
--- by @'Elem`@ type family.
-class NotFound
-
-type family Elem (a :: *) (ls::[*]) :: Constraint where
-  Elem a '[]         = NotFound
-  Elem a (a ': list) = ()
-  Elem a (b ': list) = Elem a list
-
-class HasForeign (layout :: *) where
-  type Foreign layout :: *
-  foreignFor :: Proxy layout -> Req -> Foreign layout
-
-instance (HasForeign a, HasForeign b)
-      => HasForeign (a :<|> b) where
-  type Foreign (a :<|> b) = Foreign a :<|> Foreign b
-
-  foreignFor Proxy req =
-         foreignFor (Proxy :: Proxy a) req
-    :<|> foreignFor (Proxy :: Proxy b) req
-
-instance (KnownSymbol sym, HasForeign sublayout)
-      => HasForeign (Capture sym a :> sublayout) where
-  type Foreign (Capture sym a :> sublayout) = Foreign sublayout
-
-  foreignFor Proxy req =
-    foreignFor (Proxy :: Proxy sublayout) $
-      req & reqUrl.path <>~ [Segment (Cap str)]
-          & funcName %~ (++ ["by", str])
-
-    where str = pack . symbolVal $ (Proxy :: Proxy sym)
-
-instance Elem JSON list => HasForeign (Delete list a) where
-  type Foreign (Delete list a) = Req
-
-  foreignFor Proxy req =
-    req & funcName  %~ ("delete" :)
-        & reqMethod .~ "DELETE"
-
-instance Elem JSON list => HasForeign (Get list a) where
-  type Foreign (Get list a) = Req
-
-  foreignFor Proxy req =
-    req & funcName  %~ ("get" :)
-        & reqMethod .~ "GET"
-
-instance (KnownSymbol sym, HasForeign sublayout)
-      => HasForeign (Header sym a :> sublayout) where
-  type Foreign (Header sym a :> sublayout) = Foreign sublayout
-
-  foreignFor Proxy req =
-    foreignFor subP (req & reqHeaders <>~ [HeaderArg hname])
-
-    where hname = pack . symbolVal $ (Proxy :: Proxy sym)
-          subP = Proxy :: Proxy sublayout
-
-instance Elem JSON list => HasForeign (Post list a) where
-  type Foreign (Post list a) = Req
-
-  foreignFor Proxy req =
-    req & funcName  %~ ("post" :)
-        & reqMethod .~ "POST"
-
-instance Elem JSON list => HasForeign (Put list a) where
-  type Foreign (Put list a) = Req
-
-  foreignFor Proxy req =
-    req & funcName  %~ ("put" :)
-        & reqMethod .~ "PUT"
-
-instance (KnownSymbol sym, HasForeign sublayout)
-      => HasForeign (QueryParam sym a :> sublayout) where
-  type Foreign (QueryParam sym a :> sublayout) = Foreign sublayout
-
-  foreignFor Proxy req =
-    foreignFor (Proxy :: Proxy sublayout) $
-      req & reqUrl.queryStr <>~ [QueryArg str Normal]
-
-    where str = pack . symbolVal $ (Proxy :: Proxy sym)
-
-instance (KnownSymbol sym, HasForeign sublayout)
-      => HasForeign (QueryParams sym a :> sublayout) where
-  type Foreign (QueryParams sym a :> sublayout) = Foreign sublayout
-
-  foreignFor Proxy req =
-    foreignFor (Proxy :: Proxy sublayout) $
-      req & reqUrl.queryStr <>~ [QueryArg str List]
-
-    where str = pack . symbolVal $ (Proxy :: Proxy sym)
-
-instance (KnownSymbol sym, HasForeign sublayout)
-      => HasForeign (QueryFlag sym :> sublayout) where
-  type Foreign (QueryFlag sym :> sublayout) = Foreign sublayout
-
-  foreignFor Proxy req =
-    foreignFor (Proxy :: Proxy sublayout) $
-      req & reqUrl.queryStr <>~ [QueryArg str Flag]
-
-    where str = pack . symbolVal $ (Proxy :: Proxy sym)
-
-instance HasForeign Raw where
-  type Foreign Raw = Method -> Req
-
-  foreignFor Proxy req method =
-    req & funcName %~ ((toLower method) :)
-        & reqMethod .~ method
-
-instance (Elem JSON list, HasForeign sublayout) => HasForeign (ReqBody list a :> sublayout) where
-  type Foreign (ReqBody list a :> sublayout) = Foreign sublayout
-
-  foreignFor Proxy req =
-    foreignFor (Proxy :: Proxy sublayout) $
-      req & reqBody .~ True
-
-instance (KnownSymbol path, HasForeign sublayout)
-      => HasForeign (path :> sublayout) where
-  type Foreign (path :> sublayout) = Foreign sublayout
-
-  foreignFor Proxy req =
-    foreignFor (Proxy :: Proxy sublayout) $
-      req & reqUrl.path <>~ [Segment (Static str)]
-          & funcName %~ (++ [str])
-
-    where str = Data.Text.map (\c -> if c == '.' then '_' else c) . pack . symbolVal $ (Proxy :: Proxy path)
-
-instance HasForeign sublayout => HasForeign (RemoteHost :> sublayout) where
-  type Foreign (RemoteHost :> sublayout) = Foreign sublayout
-
-  foreignFor Proxy req =
-    foreignFor (Proxy :: Proxy sublayout) req
-
-instance HasForeign sublayout => HasForeign (IsSecure :> sublayout) where
-  type Foreign (IsSecure :> sublayout) = Foreign sublayout
-
-  foreignFor Proxy req =
-    foreignFor (Proxy :: Proxy sublayout) req
-
-instance HasForeign sublayout => HasForeign (Vault :> sublayout) where
-  type Foreign (Vault :> sublayout) = Foreign sublayout
-
-  foreignFor Proxy req =
-    foreignFor (Proxy :: Proxy sublayout) req
-
-instance HasForeign sublayout => HasForeign (HttpVersion :> sublayout) where
-  type Foreign (HttpVersion :> sublayout) = Foreign sublayout
-
-  foreignFor Proxy req =
-    foreignFor (Proxy :: Proxy sublayout) req
+import Servant.API
+import Servant.Foreign.Internal
diff --git a/servant-foreign/src/Servant/Foreign/Internal.hs b/servant-foreign/src/Servant/Foreign/Internal.hs
new file mode 100644
index 00000000..1aa92af4
--- /dev/null
+++ b/servant-foreign/src/Servant/Foreign/Internal.hs
@@ -0,0 +1,261 @@
+{-# LANGUAGE CPP                   #-}
+{-# LANGUAGE ConstraintKinds       #-}
+{-# LANGUAGE DataKinds             #-}
+{-# LANGUAGE FlexibleContexts      #-}
+{-# LANGUAGE FlexibleInstances     #-}
+#if !MIN_VERSION_base(4,8,0)
+{-# LANGUAGE NullaryTypeClasses    #-}
+#endif
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE ScopedTypeVariables   #-}
+{-# LANGUAGE TemplateHaskell       #-}
+{-# LANGUAGE TypeFamilies          #-}
+{-# LANGUAGE TypeOperators         #-}
+{-# LANGUAGE UndecidableInstances  #-}
+{-# LANGUAGE OverloadedStrings     #-}
+
+-- | Generalizes all the data needed to make code generation work with
+-- arbitrary programming languages.
+module Servant.Foreign.Internal where
+
+import           Control.Lens (makeLenses, (%~), (&), (.~), (<>~))
+import qualified Data.Char    as C
+import           Data.Proxy
+import           Data.Text
+import           GHC.Exts     (Constraint)
+import           GHC.TypeLits
+import           Prelude      hiding (concat)
+import           Servant.API
+
+-- | Function name builder that simply concat each part together
+concatCase :: FunctionName -> Text
+concatCase = concat
+
+-- | Function name builder using the snake_case convention.
+-- each part is separated by a single underscore character.
+snakeCase :: FunctionName -> Text
+snakeCase = intercalate "_"
+
+-- | Function name builder using the CamelCase convention.
+-- each part begins with an upper case character.
+camelCase :: FunctionName -> Text
+camelCase = camelCase' . Prelude.map (replace "-" "")
+  where camelCase' []     = ""
+        camelCase' (p:ps) = concat $ p : Prelude.map capitalize ps
+        capitalize ""   = ""
+        capitalize name = C.toUpper (Data.Text.head name) `cons` Data.Text.tail name
+
+type Arg = Text
+
+newtype Segment = Segment { _segment :: SegmentType  }
+  deriving (Eq, Show)
+
+data SegmentType = Static Text  -- ^ a static path segment. like "/foo"
+                 | Cap Arg        -- ^ a capture. like "/:userid"
+  deriving (Eq, Show)
+
+type Path = [Segment]
+
+data ArgType =
+    Normal
+  | Flag
+  | List
+  deriving (Eq, Show)
+
+data QueryArg = QueryArg
+  { _argName :: Arg
+  , _argType :: ArgType
+  } deriving (Eq, Show)
+
+data HeaderArg = HeaderArg
+    { headerArgName :: Text
+    }
+  | ReplaceHeaderArg
+    { headerArgName :: Text
+    , headerPattern :: Text
+    } deriving (Eq, Show)
+
+
+data Url = Url
+  { _path     :: Path
+  , _queryStr :: [QueryArg]
+  } deriving (Eq, Show)
+
+defUrl :: Url
+defUrl = Url [] []
+
+type FunctionName = [Text]
+type Method = Text
+
+data Req = Req
+  { _reqUrl     :: Url
+  , _reqMethod  :: Method
+  , _reqHeaders :: [HeaderArg]
+  , _reqBody    :: Bool
+  , _funcName   :: FunctionName
+  } deriving (Eq, Show)
+
+makeLenses ''QueryArg
+makeLenses ''Segment
+makeLenses ''Url
+makeLenses ''Req
+
+isCapture :: Segment -> Bool
+isCapture (Segment (Cap _)) = True
+isCapture                _  = False
+
+captureArg :: Segment -> Arg
+captureArg (Segment (Cap s)) = s
+captureArg                 _ = error "captureArg called on non capture"
+
+defReq :: Req
+defReq = Req defUrl "GET" [] False []
+
+-- | To be used exclusively as a "negative" return type/constraint
+-- by @'Elem`@ type family.
+class NotFound
+
+type family Elem (a :: *) (ls::[*]) :: Constraint where
+  Elem a '[]         = NotFound
+  Elem a (a ': list) = ()
+  Elem a (b ': list) = Elem a list
+
+class HasForeign (layout :: *) where
+  type Foreign layout :: *
+  foreignFor :: Proxy layout -> Req -> Foreign layout
+
+instance (HasForeign a, HasForeign b)
+      => HasForeign (a :<|> b) where
+  type Foreign (a :<|> b) = Foreign a :<|> Foreign b
+
+  foreignFor Proxy req =
+         foreignFor (Proxy :: Proxy a) req
+    :<|> foreignFor (Proxy :: Proxy b) req
+
+instance (KnownSymbol sym, HasForeign sublayout)
+      => HasForeign (Capture sym a :> sublayout) where
+  type Foreign (Capture sym a :> sublayout) = Foreign sublayout
+
+  foreignFor Proxy req =
+    foreignFor (Proxy :: Proxy sublayout) $
+      req & reqUrl.path <>~ [Segment (Cap str)]
+          & funcName %~ (++ ["by", str])
+
+    where str = pack . symbolVal $ (Proxy :: Proxy sym)
+
+instance Elem JSON list => HasForeign (Delete list a) where
+  type Foreign (Delete list a) = Req
+
+  foreignFor Proxy req =
+    req & funcName  %~ ("delete" :)
+        & reqMethod .~ "DELETE"
+
+instance Elem JSON list => HasForeign (Get list a) where
+  type Foreign (Get list a) = Req
+
+  foreignFor Proxy req =
+    req & funcName  %~ ("get" :)
+        & reqMethod .~ "GET"
+
+instance (KnownSymbol sym, HasForeign sublayout)
+      => HasForeign (Header sym a :> sublayout) where
+  type Foreign (Header sym a :> sublayout) = Foreign sublayout
+
+  foreignFor Proxy req =
+    foreignFor subP (req & reqHeaders <>~ [HeaderArg hname])
+
+    where hname = pack . symbolVal $ (Proxy :: Proxy sym)
+          subP = Proxy :: Proxy sublayout
+
+instance Elem JSON list => HasForeign (Post list a) where
+  type Foreign (Post list a) = Req
+
+  foreignFor Proxy req =
+    req & funcName  %~ ("post" :)
+        & reqMethod .~ "POST"
+
+instance Elem JSON list => HasForeign (Put list a) where
+  type Foreign (Put list a) = Req
+
+  foreignFor Proxy req =
+    req & funcName  %~ ("put" :)
+        & reqMethod .~ "PUT"
+
+instance (KnownSymbol sym, HasForeign sublayout)
+      => HasForeign (QueryParam sym a :> sublayout) where
+  type Foreign (QueryParam sym a :> sublayout) = Foreign sublayout
+
+  foreignFor Proxy req =
+    foreignFor (Proxy :: Proxy sublayout) $
+      req & reqUrl.queryStr <>~ [QueryArg str Normal]
+
+    where str = pack . symbolVal $ (Proxy :: Proxy sym)
+
+instance (KnownSymbol sym, HasForeign sublayout)
+      => HasForeign (QueryParams sym a :> sublayout) where
+  type Foreign (QueryParams sym a :> sublayout) = Foreign sublayout
+
+  foreignFor Proxy req =
+    foreignFor (Proxy :: Proxy sublayout) $
+      req & reqUrl.queryStr <>~ [QueryArg str List]
+
+    where str = pack . symbolVal $ (Proxy :: Proxy sym)
+
+instance (KnownSymbol sym, HasForeign sublayout)
+      => HasForeign (QueryFlag sym :> sublayout) where
+  type Foreign (QueryFlag sym :> sublayout) = Foreign sublayout
+
+  foreignFor Proxy req =
+    foreignFor (Proxy :: Proxy sublayout) $
+      req & reqUrl.queryStr <>~ [QueryArg str Flag]
+
+    where str = pack . symbolVal $ (Proxy :: Proxy sym)
+
+instance HasForeign Raw where
+  type Foreign Raw = Method -> Req
+
+  foreignFor Proxy req method =
+    req & funcName %~ ((toLower method) :)
+        & reqMethod .~ method
+
+instance (Elem JSON list, HasForeign sublayout) => HasForeign (ReqBody list a :> sublayout) where
+  type Foreign (ReqBody list a :> sublayout) = Foreign sublayout
+
+  foreignFor Proxy req =
+    foreignFor (Proxy :: Proxy sublayout) $
+      req & reqBody .~ True
+
+instance (KnownSymbol path, HasForeign sublayout)
+      => HasForeign (path :> sublayout) where
+  type Foreign (path :> sublayout) = Foreign sublayout
+
+  foreignFor Proxy req =
+    foreignFor (Proxy :: Proxy sublayout) $
+      req & reqUrl.path <>~ [Segment (Static str)]
+          & funcName %~ (++ [str])
+
+    where str = Data.Text.map (\c -> if c == '.' then '_' else c) . pack . symbolVal $ (Proxy :: Proxy path)
+
+instance HasForeign sublayout => HasForeign (RemoteHost :> sublayout) where
+  type Foreign (RemoteHost :> sublayout) = Foreign sublayout
+
+  foreignFor Proxy req =
+    foreignFor (Proxy :: Proxy sublayout) req
+
+instance HasForeign sublayout => HasForeign (IsSecure :> sublayout) where
+  type Foreign (IsSecure :> sublayout) = Foreign sublayout
+
+  foreignFor Proxy req =
+    foreignFor (Proxy :: Proxy sublayout) req
+
+instance HasForeign sublayout => HasForeign (Vault :> sublayout) where
+  type Foreign (Vault :> sublayout) = Foreign sublayout
+
+  foreignFor Proxy req =
+    foreignFor (Proxy :: Proxy sublayout) req
+
+instance HasForeign sublayout => HasForeign (HttpVersion :> sublayout) where
+  type Foreign (HttpVersion :> sublayout) = Foreign sublayout
+
+  foreignFor Proxy req =
+    foreignFor (Proxy :: Proxy sublayout) req