> module Frame.Data (
>   Data (..)
> ) where

> import Frame.GUI
> import qualified Data.ByteString.Lazy as L

> -- | A collection of views which can be streamed to the client by the server
> data Data 
>      = View GUI             -- ^ A full view
>      | ViewPart [Container] -- ^ A partial view
>      | File L.ByteString    -- ^ A file
>      | Error404             -- ^ File not found, 404 HTTP response
>      | Redirect URL         -- ^ Redirection

> instance Composable Data where
>   (View g) <+ c      = View $ g <+ c
>   (ViewPart cs) <+ c = ViewPart $ cs ++ [c]
>   d <+ _             = d
>   c +> (View g)      = View $ c +> g
>   c +> (ViewPart cs) = ViewPart $ (c:cs)
>   _ +> d             = d