Haskell is a programming language that can implement the entire range of computation from very abstract set-theoretical mathematical expressions to high performance numeric processing. From a computer science point of view it is a functional programming language that very elegantly allows procedural programming (via monads).
An excellent book The Haskell Road to Logic, Math and Programming, by Kees Doets and Jan van Eijck, introduces the reader to Haskell from a mathematical perspective. In particular, read Chapter 1 ‘Getting Started’, Chapter 2 ‘Talking about Mathematical Objects’, Chapter 4 ‘Sets, Types and Lists’, Chapter 5 ‘Relations’ and Chapter 6 ‘Functions’.
Note that the hugs Haskell interpreter used in the book has been superseded by the Glasgow Haskell interpreter (available at Haskell downloads).
For other Haskell tutorials see Haskell documentation.