Internal.hs

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{-# LANGUAGE DeriveDataTypeable        #-}
{-# LANGUAGE ExistentialQuantification #-}
module Patat.Images.Internal
    ( Config (..)
    , Backend (..)
    , BackendNotSupported (..)
    , Handle (..)
    ) where


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import           Control.Exception (Exception)
import qualified Data.Aeson        as A
import           Data.Data         (Data)
import           Data.Typeable     (Typeable)


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data Config a = Auto | Explicit a deriving (Eq)


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data Backend = forall a. A.FromJSON a => Backend (Config a -> IO Handle)


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data BackendNotSupported = BackendNotSupported String
    deriving (Data, Show, Typeable)


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instance Exception BackendNotSupported


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data Handle = Handle
    { hDrawImage  :: FilePath -> IO ()
    }