A simple “zoom” which works in MonadState

[neongreen]

zoom'
  :: MonadState s m
  => LensLike' (Zoomed (State s) a) s t -> StateT t Identity a -> m a
zoom' l = state . runState . zoom l

This function could be useful when you just want to edit the state quickly and don't need to do anything specific to the monad you're actually working in.

[WorldSEnder]

I use l %%= runState modification for this, where modification :: State t a. Especially with BlockArguments it's not that unreadable, for example the following works fine for me

localEnv :: Lens' GlobalEnv LocalEnv
nextFreeId :: Lens' LocalEnv Int
bindings :: Lens' LocalEnv (Map Int Foo)
Reserved :: Foo

localEnv %%= runState do
  newId <- nextFreeId <+= 1
  bindings . at newId <?= Reserved