type Env = { ... }
newtype AppM a = AppM (ReaderT Env Aff a)

runAppM ∷ Env → AppM ~> Aff
runAppM env (AppM m) = runReaderT m env

instance monadAskAppM ∷ TypeEquals e Env => MonadAsk e AppM where
  ask = AppM $ asks from

class TypeEquals a b | a -> b, b -> a where
  to :: a -> b
  from :: b -> a

instance refl :: TypeEquals a a where
  to a = a
  from a = a

Note: any instance will necessarily overlap with
`refl` below, so instances of this class should
not be defined in libraries.

from :: e → Env
ask :: AppM e

asks :: MonadAsk e AppEnv => (e -> Env) -> AppM Env