haskell - How best to type "Any monad transformer stack containing m" -

i'd write function

fixproxy :: (monad m, proxy p) => (b -> m b) -> b -> () -> p a' () b m r fixproxy f () = runidentityp $   v  <- respond   a' <- lift (f a)   fixproxy f a' v 

which works you'd think until try run proxy

>>> :t \g -> runrvart . runwritert . runproxy $ fixproxy g 0 >-> tolistd (num a, randomsource m s, monadrandom (writert [a] (rvart n)),   data.random.lift.lift n m) =>  (a -> writert [a] (rvart n) a) -> s -> m (a, [a]) 

where use rvart intentionally highlight existence of lift class in rvar. lift represents existence of natural transformation n :~> m ought encapsulate i'm looking for, function like:

fixproxy :: (monad m, monad n, lift m n, proxy p)              => (b -> m b) -> b -> () -> p a' () b n r 

is lift right answer (which require many orphan instances) or there more standard natural transformation mptc use?

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note practical solution, described in comments below, like

runrvart . runwritert . runproxy  $ hoistk lift (fixproxy (const $ sample stduniform) 0) >-> tolistd