On 11 May 2015 at 22:50, Tara Athan
Hi - I am new to this list, and the only archive I could find is the Mailman archive, which is next to impossible to search. So this may be a topic that has been previously discussed, I don't know...
The documentation at https://hackage.haskell.org/package/containers-0.3.0.0/docs/Data-Tree.html says that a rose tree is another name for multiway tree. But this is not true according to my understanding of the accepted definition in the CS literature (see e.g. http://doc.utwente.nl/66626/1/db-utwente-0000003528.pdf) Rose trees do not have labels at the nodes, only at the leaves (aka tips).
There are various different definitions of tree structures (I once started a literature review of this, but never finished it). Note that if you allow values in all nodes, you can always represent a tree where only leaves have values of type `a' as an arbitrary tree with nodes of type `Maybe a' (but you can't statically enforce this, at least with the definition in Data.Tree: for that, you would have to generalise the tree structure even more to have a distinct type variable just for the leaf nodes with a new constructor, thus complicating usage of the data structure). -- Ivan Lazar Miljenovic Ivan.Miljenovic@gmail.com http://IvanMiljenovic.wordpress.com