An attempt to figure out an easy way to serialize function types.

ClosureSerialization.hs

{-# OPTIONS -XExistentialQuantification -XMultiParamTypeClasses #-}

-- Serialization requires being able to marshall and unmarshall.
class Serializable a where
  serialize   :: a -> String
  deserialize :: String -> (a, String)

-- Static assertion that `a` encodes `b -> c`.
class Encoding a b c where
  decode :: a -> b -> c

-- Represents a serializable function by an encoding `t`. To make a
-- datatype serializable, replace all `a -> b` by `F a b`.
data F a b = 
  forall t. (Serializable t, Encoding t a b) =>
  F { unF :: t }
    
-- Proof that all function encodings are serializable.  
instance Serializable (F a b) where
  -- Serialization is delegated to the encoding.
  serialize (F x) = serialize x
  
  -- Deserialization *FAILS* because we do not know the type `t` of
  -- the encoding.  Is it possible to *READ* the type `t` from the
  -- data stream too?  And coerce it to `Serializable t`?
  deserialize s   = undefined