[Hat] Hat-Gui, new tool

[Olaf Chitil]

Neil Mitchell wrote:

> I have started writing Hat-Gui, a screenshot is available at:
> http://www-users.cs.york.ac.uk/~ndm/projects/hat-gui.png

Great! For the interactive tools a GUI will be even better.

> What is the best way to acheive this split, and how should it be
> organised? Most of the tools are already relatively abstract -
> although will probably need tweaks.

I agree that splitting every tool module into a "model" module with a 
nice API and a textual "view" module is a very good idea. I wouldn't yet 
introduce any directory hierarchy (the hierarchical name space isn't 
Haskell 98 anyway). I think it would be slightly more meaningful if the 
models would keep the original names and the views be named e.g. 
HatStackText.

Do you plan extensions of the user interface? For a long time I thought 
it would be nice to make hat-observe source-oriented: Make it a source 
browser in which you can mark any expression and then this expression is 
observed. This could even be combined with hat-cover, because obviously 
you should not be able to observe a slice of code that was never executed.

Ciao,
Olaf