Some common Hugs error messages. Haskell - Wikibooks, collection of open-content textbooks. Haskell is a functional programming language. If you've programmed before and would like to see a little bit of how Haskell works and is different from other programming languages, see the overview. Haskell is unique in two ways. First, it is a pure functional programming language. If you have a function and you call it twice in two different places with the same arguments then it will return exactly the same value both times. Second, Haskell provides a very modern type system which incorporates features like typeclasses and generalized algebraic data types. (we hope terms like these will roll smoothly off your tongue by the time you're done.)
So, why do Haskellers like their language? In this book we aim to introduce you both to the Haskell language, from the very basics to the most advanced features, and to computer programming in general. Overview[edit] Beginner's Track[edit] Most chapters contain exercises where you can test yourself on what you learned in that chapter. Syntactic sugar. Haskell - langref.org. GHC Documentation. Haskell Hierarchical Libraries.