John Meacham john at
Sat Oct 21 23:12:16 EDT 2006

On Sat, Oct 21, 2006 at 03:29:57PM +0200, Josef Svenningsson wrote:
> Hi,
> I'd like to propose to include the following function in Data.List:
> join :: [a] -> [[a]] -> [a]
> join x xs = concat (intersperse x xs)
> I find that every time I use intersperse I also concat the result. And
> it seems that I'm not alone:
> A clear majority of all the uses of intersperse also use concat on the
> result. I think it seems worthwhile to give a name to that idiom.
> The name 'join' was taken from Data.ByteString, where a similar function 
> exists.
> All the best,

I have that same function in my standard toolbox, but call it


a la concatMap.

though mconcatInter would probably be better, since then we can do it
for an arbitrary monoid.


John Meacham - ⑆⑆john⑈

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