Lorenzo Bolla wrote:

Your scripts stack-overflows on my box.

I've made 2 little changes, to ensure strictness. I believe your
"insertList" is building up a huge list of thunks.

import Data.Foldable (foldr')
<snip>
main :: IO ()
main = putStrLn $ show $ maxTree $ foldr' insert Empty toInsert

Better?

Huh, why foldr' and not Data.List.foldl' ? As far as I understand, the former has to evaluate the whole spine of the list first before it can begin to assemble the tree. The latter can start building trees right away.