Enyria

typedef StateTransfomer s a = s -> (s, a)

data _IST s a = Fin s a | Cont s (s -> _IST s a)

typedef InspectedState s a as s -> (_IST s a)

InspectedState instanceof Monad where
return x = \s -> Fin s x

>>= t f = \s -> switch t s:
case Fin x a : Fin f a x
case Cont x a : Cont x (>>= a f)

stop :: InspectedState s a

stop = \s -> CONT s (s -> Fin s _)

get :: _ -> InspectedState s a
get _ = \s -> Fin s s

set :: a -> InspectedState s a
set a = \s -> Fin a

execStep :: _IST s a -> _IST s a

execStep Fin a b = Fin a b
execStep Cont s t = t s

--------

If you are still reading, contact me...