I want to learn a functional programming language, hoping to start off with HASKELL. any suggestions?

If you really want Haskell I recommend the Haskell Book. haskellbook.com

It is recent and easy to understand.

Learn by doing.

Get the basics first, and then expand your knowledge as you encounter problems that need resolving.

Only when you are comfortable with the language should you start exploring it's more advanced features.

There are many monad tutorials out there. Ignore them until you need to understand what a monad is. At that point, go read the "You Could Have Invented Monads" post by the tech blogger sigfpe.

Scala

go

Learn You A Haskell For Great Good