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