I can understand that "advanced" python programs may be difficult to understand for beginners (lots of implicit/hidden behaviors, possibility to change basically everything one should expect, etc).

But to _learn_ programming, I really, really don't see how using Haskell would be simpler than Python. Perhaps if you have a specific background (e.g., math), but else python is almost pseudo code already. You'll really have to convince me that a more abstract language is better...

Haskell’s hard to interpret error messages alone disqualify it from being a beginner language.

Python: errors based on incorrect indentation (many beginners don’t use nice IDEs), or don’t understand the meaning of the hints) and scope (don’t forget your “global” if you’re hacking in PyGame) are challenges.