> Ehm... what? How can you do such a replacement without losing, for
> example, functions like this:
> f (KI s h) i = snd $ h i $ fst $ h i s
Well, if we eliminate the existential from
data Kl i o = forall s. Kl s (i -> s -> (s, o))
following strictly the procedure we obtain
data S i o = S (i -> (S i o, o))
It is the data type of infinite streams, with an extra input. Your
function is obtaining the second element of the stream (assuming the
constant input i). Infinite streams form a monad, as described in
great detail here:
http://patternsinfp.wordpress.com/2010/12/31/stream-monad/
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