This portal points to places where you can go if you want to learn Haskell.
The Introduction to Haskell on the Haskell website tells you what Haskell gives you: substantially increased programmer productivity, shorter, clearer, and more maintainable code, fewer errors, higher reliability, a smaller semantic gap between the programmer and the language, shorter lead times. There is an old but still relevant paper about Why Functional Programming Matters (PDF) by John Hughes. More recently, Sebastian Sylvan wrote an article about Why Haskell Matters.
There is also a table comparing Haskell to other functional languages. Many questions about functional programming are answered by the comp.lang.functional FAQ.
You can ask questions to members of the haskell community on maillists, IRC, or StackOverflow.
Here is an overview about Haskell implementations (for new, or non-expert users, we recommend starting with the Haskell Platform).
|GHC||+||-||++||Many language extensions; generated code is very fast. The most popular implementation.|
|Hugs||+/-||++||-||Fast compilation; used a lot for learning Haskell and rapid code development. See also WinHugs.|
|nhc98||+||+||++||Profiling, debugging, tracing. Not actively developed.|
|Yhc||+||+||?||Compiles to bytecodes. Runtime easily portable. Not actively developed.|
|Helium||++||++||-||No type classes (yet!) and thus incompatible with most material on this site. Made for teaching/learning. Excellent error messages.|
|UHC||+/-||-||+/-||Developed for experimentation with language features. As a Haskell compiler still under development.|
Detailed information on the implementations can be found in a separate article.
Below there are links to certain introductory material. If you want to dig deeper, see Books and tutorials.
- The Haskell School of Expression
- Haskell: the Craft of Functional Programming
- Introduction to Functional Programming using Haskell
- An Introduction to Functional Programming Systems Using Haskell
- Algorithms: A functional programming approach
- The Haskell Road to Logic, Maths, and Programming
- Programming in Haskell
-  Real World Haskell
- Haskell Wikibook A long tutorial on Haskell that includes "Yet Another Haskell Tutorial", "Write Yourself a Scheme in 48 Hours" and "All about monads".
- YAHT - Yet Another Haskell Tutorial (good tutorial available online, also here)
- Two dozen short lessons
- A Gentle Introduction to Haskell - classic text, but not so gentle really :D
- Online Haskell Course (German)
- Haskell for C Programmers
- Learn You a Haskell for Great Good! Beautiful, illustrated Haskell tutorial for programmers with less of a functional programming background.
- Hitchhikers guide to Haskell
- Write Yourself a Scheme in 48 Hours
- Tackling the Awkward Squad (on I/O, interfacing to C, concurrency and exceptions)
- You Could Have Invented Monads! (And Maybe You Already Have.)
- Monads for Functional Programming
- All about monads
- IO inside: down the Rabbit Hole
- The paper that at first time introduced type classes and their implementation using dictionaries
- More papers on the type classes
- The official language definition: Language and library specification
- Haskell Newbie
- Tour of the Haskell Prelude
- Haskell Reference
- Haskell Reference card
- A tour of the Haskell Monad functions
- Tour of the Helium Prelude
- Some common Hugs error messages
- The Haskell Cheatsheet - A reference card and mini-tutorial in one.
- Introduction to Functional Programming, Chalmers
- Programming in Haskell, Chalmers
- Advanced Functional Programming, Chalmers
- [Dead link] Advanced Advanced Functional Programming, Chalmers
- CS 11 Caltech
- Functional programming: course notes (English, Dutch, Spanish), slides in Dutch
- CS1011: Tutorials, lab exercises and solutions
- [Hungarian] Functional Programming: online Haskell exercises (maybe Explorer can't show xml content)