[Haskell] Displaying trees in Haskell

Hello, I am quite new to Haskell and I am seeking the best way to display trees graphically when using Haskell. I have looked on the web, but am still not clear! For those interested, please find more detailed information below. Regards, Luana Fagarasan Further information: I am writing a theorem prover in Haskell as my final year project. This is very loosely based on the HAL theorem prover described in "ML for the working programmer" by Larry Paulson. I would like to display the proof tree (containing the main goal as the root and subgoals that were developed along the way as leaves/nodes), once a proof is found. More generally I would be interested in understanding more about GUIs when using Haskell.