I am not sure what you mean. Tutorials can only deal with toy examples. Once you understand them, then you can (and you should) write bigger projects. About Carmack, that's exactly what he did, he implemented Wolf3D in Haskell to have a real impression about Haskell. (Assuming you're talking about this video where he discuss functional programming for games)
Aren't you just being lazy? :)
Edit: that video:
http://functionaltalks.org/2013/08/26/john-carmack-thoughts-...