Combinations Tree

gistfile1.hs

import Data.List
import Data.Tree

combinationsTree xs = unfoldTree next ([], xs)
  where next (path, xs) = (path, map (appendTo path . splitAt 1) $ init $ tails xs)
        appendTo path (x, ys)  = (path ++ x, ys)

depth 0 node = Node{rootLabel=(rootLabel node), subForest=[]}
depth n node = node{subForest=(map (depth (n - 1)) (subForest node))}