Functional programming is famous for being hard. But it also comes with huge rewards! 😮
First of all, your programming style will get better 😎. Don't we all want that?
Second, functional languages are REALLY powerful. Like, you won't even believe how many awesome features functional languages have. Like, for example, pattern matching!
If you're not ready for Haskell (basically functional programming hard mode), I recommend F#. It's a .NET language, so it does have a lot of imperative aspects, plus its documentation is good and the community is willing to help you.
But enough about that. To use this program, type "insert <any integer>" when it prompts you (There's no arrow or anything, but the program begins after "mono main.exe" appears on the console). It'll print the tree out.