[Haskell-cafe] What class for splittable data / balanced-fold?

Ryan Newton rrnewton at gmail.com
Sat Sep 28 19:09:06 CEST 2013

Hi all,

We all know and love Data.Foldable and are familiar with left folds and
right folds.  But what you want in a parallel program is a balanced fold
over a tree.  Fortunately, many of our datatypes (Sets, Maps) actually ARE
balanced trees.  Hmm, but how do we expose that?

It seems like it would be nice to have a* standard class t*hat allows you
to split a datatype into roughly even halves, until you get down to the
leaves.  This goes along with Guy Steele's argument that we should use
"append lists" as primitive rather than "cons-lists", and it's why we
added append-lists
within the monad-par

Does this class exist already?  A random google search brought up this
module by the name
but it's not quite the right thing.

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