Blogger - Folding tree - 3 (Haskell)

import TreeToList
import Criterion.Main

-- prepare data
generateTree :: [a] -> Tree a
generateTree list = case list of
  []     -> Empty
  (x:xs) -> let lr = generateTree(xs) in lr `seq` Node x lr lr

tree :: Tree Int
tree = generateTree [1..20]

-- benchmark
benchmark = bench "tree to list" $ nf toList tree
main = defaultMain [benchmark]