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supki/eblo.hs

Created September 9, 2014 21:04
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EBLO
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eblo.hs
newtype FromJSON_ a = FromJSON_ { _parseJSON :: Value -> Parser a }
newtype T a s = T { unT :: a }
instance Reifies s (FromJSON_ a) => FromJSON (T a s) where
parseJSON = fmap T . _parseJSON (reflect (Proxy :: Proxy s))
parseJson :: forall a. (Value -> Parser a) -> ByteString -> Maybe a
parseJson f b = reify (FromJSON_ f) (\(_ :: Proxy s) -> fmap unT ((decode :: ByteString -> Maybe (T a s)) b))
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