Re: [Haskell-cafe] Std lib equivalent for liftM concat . sequence

Alistair Bayley wrote:

...

concatM :: Monad m => [m [a]] -> m [a] concatM = liftM concat . sequence

Miguel Mitrofanov wrote:

Seems to be close to sequence :: [ListT m a] -> ListT m a Hmm?

Yes. It is close to something like that for the old broken ListT - but let's not talk about that one. For "ListT done right", how about: concatM :: Monad m => [ListT m a] -> List m a concatM = join . liftList (http://www.haskell.org/haskellwiki/ListT_done_right) Regards, Yitz