Re: Various folds in the containers package

Duncan Coutts writes:

So I suggest all four folds. They are all useful and can all be implemented efficiently.

For certain classes of operation ⓧ, a tree-fold (( _ ⓧ _) ⓧ (_ ⓧ _)) gives better complexity. Is there room for that, or is it too difficult to decide what to do about the unbalanced parts? -- Jón Fairbairn Jon.Fairbairn@cl.cam.ac.uk