Very good points. Since C++ is a good match for the way people are taught to think about programming, it's obvious that anything good programmers can't easily

Very good points. Since C++ is a good match for the way people are taught to think about programming, it's obvious that anything good programmers can't easily and consistently get right is the fault of the language. With Haskell, you can't rule out unfamiliarity as the cause of any difficulties until you're already heavily invested in it. Most people really have no basis for challenging the statement that Haskell is perfectly suited for game programming in the hands of a competent programmer. Pragmatically, for the OP, I think it's safe to say that C++ and Haskell are both very challenging languages that take a long time to master. The advantage of C++ is that there's ample evidence of its suitability for various domains. The advantage of Haskell is that you'll learn a different way of programming. The decisive factor may be whether it's your own money on the line.