Норм придумал? type IOObject a = (IO a, a -> IO ()) -- FIXME sane errors heterObj :: IOObject a -> IOObject a -> IOObject a heterObj a b = (fst a, snd b) nulls :: IOObject a nulls = (throw $ Underflow, const $ return ()) chans :: Chan a -> IOObject a chans a = (readChan a, writeChan a) type DataTypeObject a = (a -> ByteString, ByteString -> a) lazyByteStrings :: DataTypeObject ByteString lazyByteStrings = (id, id) showBool True = "true" showBool False = "false" readBool s | s == "1" = True | s == "true" = True | s == "0" = False | s == "false" = False booleans :: DataTypeObject Bool booleans = (showBool, readBool) simpleFile :: forall a m. (Monad m, EmbedIO m) => String -> IOObject a -> DataTypeObject a -> NineFile m simpleFile name (rd, wr) (rdc, wrc) = (boringFile name :: NineFile m) { read = simpleRead $ liftM rdc $ rd, write = simpleWrite $ wr . wrc }