What is the best usage of haskell in terms of build-in capabilities or external libraries?

[Henning Thielemann]

On Tue, 18 Dec 2012, Peng Yu wrote:

> After reading some wiki pages of haskell, it is not clear to what area
> haskell is really good for. One strong point seems to be a testbed for
> trying new languages. But this seems to be the case for other
> functional languages as well.
>
> Is there an application area in which haskell is much stronger than
> other different languages?

Difficult to say, since Haskell wants to be a general purpose language. 
Haskell is strong in writing correct software. Thus you might phrase it 
like: Haskell is strong in applications where correctness counts.