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

Miguel Mitrofanov miguelimo38 at yandex.ru
Fri May 16 13:51:40 EDT 2008


Oops, I was very wrong. Sorry.

On 16 May 2008, at 20:13, Miguel Mitrofanov wrote:

> Seems to be close to
>
> sequence :: [ListT m a] -> ListT m a
>
> Hmm?
>
> On 16 May 2008, at 14:12, Alistair Bayley wrote:
>
>> A couple of days ago I had need for:
>>
>>> concatM :: Monad m => [m [a]] -> m [a]
>>> concatM = liftM concat . sequence
>>
>> but found no such thing in the std libs, except perhaps for msum (I
>> don't want to add instances for MonadPlus. Should I have to?). Have I
>> missed something trivial?
>>
>> Alistair
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