I know Haskell quite well but never reach for it when programming. Languages like F# and ocaml gives me most of the benefits of functional programming without having to deal with the unpredictability of lazy evaluation and the 10 level deep pollution of a single IO call. Also, when it comes to leading edge type systems, Haskell is falling behind. Dependently Typed languages like Agda and Idris are way more interesting from an advanced type system point of view.