This characterisation of Haskell bugs me a lot, because most reputable mathematicians would have nothing to do with Haskell either. The mathematical parts of Haskell seem to attract logicians, not general mathematicians. General mathematiicians much prefer Sage or Mathematica.
Don't get me wrong, Haskell is a great language, but it's not very "mathematical". It just has terrible ambassadors that give the impression that category theory and Haskell are synonymous. They're not, Haskell has its own breed of categeory theory that I prefer to call Haskellory theory.
This is a reasonable introduction to Haskell that does away with that Haskegorical nonsense: