[Haskell] Debugging in Haskell?

[Peter Rosenbeck]

I am a seasoned Smalltalk programmer (> 15 years experience) with a strong
background in Lisp, Scheme and Prolog. I discovered Haskell because it is
used in a computer science class of my daughter and she needed some help fom
me.

Let me first tell you that I am very much excited by the concepts and the
elegance of the language. At he same time, I'm quite disappointed about the
development environment that comes with GHCI and Hugs (the only systems
which I had a closer look at). Compared to PLT Scheme (not to mention
Smalltalk) this feels very antiquated. No trace, no symbolic debugging, no
breakpoints. I admit that all necessary error information is contained  in
what the type checker gives you, but there is no way to understand these
before one has mastered the language, which is quite hard for me and almost
impossible for a beginner.

Although, I am a fervent advicate of test driven development. I understand
that a Haskell believer would prefer proof over test and I agree in
principle, but how would a Haskell developer prove properties of a graphical
user interface?

Is therer something I missed? Is there an implementation of the
UnitTest-Framework which is so popular in the OO community. Where can I get
help?

Thanks in advance
Peter