Modern C++ is a moving target. By the time you get around to doing a project with one set of features they've been made redundant. Exceptions are a good example of this with noexcept etc coming in and replacing what went before.

I know nothing of haskell. My point is that you should learn the features of the codebase you work on, and it's a waste of time to learn all features, ultimately for a codebase you are not working on or may never work on.

incidentally, ditto, i used to have your attitude.