Multiple MonadReader constraints on a single method - haskell

Question

It doesn't look like anything stops you from defining a function like this:
tmp :: (MonadReader Int m, MonadReader Bool m) => m Int
tmp = ifM ask ((+1) <$> ask) ((+2) <$> ask)
So would be something like a typeable context, where as long as you give it a type, ask will give you the part of the environment with that type, which I think is a reasonable alternative to name shadowing.
However, with the default instances of MonadReader defined by Control.Monad.Reader, it doesn't look like there's a way to actually invoke this method. So I defined a new module that attempts to do this:
{-# LANGUAGE FlexibleInstances, MultiParamTypeClasses,
UndecidableInstances #-}
{-# OPTIONS_GHC -fno-warn-orphans #-}
module Control.Monad.Reader.Extra
( MonadReader(ask)
) where
import Control.Monad.Reader (MonadReader(ask, local, reader))
import Control.Monad.Trans.Class (MonadTrans(lift))
instance {-# OVERLAPPABLE #-} ( Monad m
, MonadTrans t
, Monad (t m)
, MonadReader r m
) =>
MonadReader r (t m) where
ask = lift ask
local _ _ = undefined
reader f = lift (reader f)
As long as this second instance is in scope, you'll be able to run tmp, like runReaderT (runReaderT tmp 1) True.
Unfortunately, I can't figure out a decent implementation for local, since it needs to have the type local :: (r -> r) -> (t m a) -> (t m a), but it doesn't seem like there's a way to lift a local :: (r -> r) -> m a -> m a to this.
What would be a reasonable implementation for local for this instance?
Minimal Complete example:
{-# LANGUAGE FlexibleInstances, MultiParamTypeClasses, UndecidableInstances, LambdaCase, FlexibleContexts #-}
module Tmpfundep where
import Control.Monad.Reader
( MonadReader(ask, local, reader)
, ReaderT(ReaderT)
, runReaderT
)
instance {-# INCOHERENT #-} (Monad m, MonadReader r m) =>
MonadReader r (ReaderT r' m) where
ask = ReaderT (const ask)
local f (ReaderT m) = ReaderT (local f . m)
reader f = ReaderT (const (reader f))
withEnv :: r -> ReaderT r m a -> m a
withEnv r m = runReaderT m r
tmp :: (MonadReader Int m, MonadReader Bool m) => m Int
tmp = ask >>= \case
True -> (+1) <$> ask
False -> (+2) <$> ask
main :: IO ()
main = withEnv True (withEnv (1 :: Int) tmp) >>= print
Was able to run this with echo main | stack exec -- runghc Tmpfundep.hs