Haskell used to be the introductory language at UT Austin a few years ago IIRC. So it's been done before. The point of an introductory programming class is not

Haskell used to be the introductory language at UT Austin a few years ago IIRC. So it's been done before. The point of an introductory programming class is not to teach a language for vocational purposes, but to teach the basics of computation. Someone who understands computation can reasonably be expected to pick up most languages.