Hello again, There were a few details I accidentally omitted from my initial email. I've attached my code again. As I mentioned in my first message on this subject, I'm just after some guidance on ways to improve upon what I've written. How can I make it clearer, more concise?? Here's a transcript of a ghci session showing how I generate a tree from a list of associations: *AssocTree> let related = filterUnrelated assocs *AssocTree> let t = growTree ( Node r [] ) related *AssocTree> printTree t root | +- C | | | +- f | | | +- e | | | | | `- m | | | `- D | | | +- g | | | | | +- i | | | | | `- j | | | | | `- k | | | `- h | +- B | `- A