Well, the existence of SICP suggests that functional languages can be used as introductory material. Scheme is perhaps more approachable than Haskell, however.
Haskell seems to have a reputation for being “difficult” to learn, but people tend to forget that classic imperative programming is difficult to learn as well. Many people struggle at first with the concept of assigning a value to a variable, and a surprising number of programmers never actually do become comfortable with pointers and indirect references.
The connections between Haskell and abstract mathematics don’t really matter as much as people sometimes assume, but for someone interested in the math anyway, looking at the analogies might provide an interesting bonus.