[Haskell-cafe] Join a transformer

[Michael Snoyman]

I'm wondering if this pattern exists and has a name. We have the concept of
joining a Monad:

join :: Monad m => m (m a) -> ma

How about joining a monad transformer?

joinT :: (Monad m, MonadTrans t) => t (t m) a -> t m a

I believe implementing this in terms of MonadTransControl[1] might be
possible, but I was wondering if there's an already existing idiom for this.

Michael

[1]
http://haddocks.fpcomplete.com/fp/7.4.2/20130301-40/monad-control/Control-Monad-Trans-Control.html
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