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Edward Kmett writes:

Data.Tuple already contains swap.

Yeah, and I'm finding it just fine with Hoogle now. I'm not sure how I was led into thinking it didn't exist, but I had reached for it one day and my hands came up empty.

    compose :: [(a -> a)] -> a -> a     compose = foldr (.) id

    composeM :: [(a -> m a)] -> a -> m a     composeM = foldr (<=<) return

The composition of them is obvious, and the suggested names already exist commonly in a lot of third party code for all sorts of purposes.

The pain of adoption plus the annoyance of trying to find them exceeds, to me, the utility of adding them.

Fair enough. It does seem that the idiom deserves a name, though, considering how often I've come across it, but perhaps that ship has sailed. -- John Wiegley FP Complete Haskell tools, training and consulting http://fpcomplete.com johnw on #haskell/irc.freenode.net

On Tue, Nov 20, 2012 at 3:09 PM, Dan Burton wrote:

The name for this is clearly mconcat, we just have to indicate which mconcat it is: the mconcat a la Endofunctors and Kleisli... whatevers, respectively. It seems like this sort of thing should be handled by the "newtype" package, but I can't seem to wrangle it into submission.

I'd be happy to take any needed steps to prepare or help push that package to some place more visible/useful. -- Darius Jahandarie

On 11/20/12 2:23 PM, Edward Kmett wrote:

On Tue, Nov 20, 2012 at 2:14 PM, John Wiegley wrote:

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compose :: [(a -> a)] -> a -> a compose = foldr (.) id

composeM :: [(a -> m a)] -> a -> m a composeM = foldr (<=<) return

I would actually consider these to fall beneath the "Fairbairn threshold".

The composition of them is obvious, and the suggested names already exist commonly in a lot of third party code for all sorts of purposes.

The pain of adoption plus the annoyance of trying to find them exceeds, to me, the utility of adding them.

Ditto. There's nothing especially interesting/unintuitive about the implementation, and while it occurs it's far from common enough to be worth the cost. So -1 from me. -- Live well, ~wren