Overview :: This is an example of a low-level binding to a c++ GUI library and a mid-level abstraction over it. This was created primarily to spark discussion in the gui@haskell.org mailing list and secondarily to provide a simple example that can be compiled using ghc without any language extensions. I encourage those who code, to implement their ideas for the Common GUI API using this simple framework. This would allow all reviewers to understand exactly what you are talking about by running your examples. Fltk was chosen for its simplicity and portability. I didn't use an existing library because I wanted a short example where the source code is easy to comprehend at all levels. Questions :: 1) How does the interface look in Test_midlevel.hs? Is there any critiques in regard to using this style in CGA (Common GUI API)? 2) What drastic or minor changes would have to be made to the Test_midlevel.hs file to make it CGA compatible? Yes, this is a completely subjective question. In your opinion, what should Test_midlevel.hs look like? 3) There has been some discussion about using non-standard Haskell extensions in CGA. No extensions have been used in this example. Exactly what extensions would be useful in this example or in CGA as a imaginary whole? Is it worth it to use said extensions and allow CGA to be incompatible with Haskell98? 4) Haskell has one namespace, the global one. Since there would be a lot of function names and attributes in CGA, their names should be well thought out. Is there any initial ideas on how to handle this? 5) I am willing to implement more stuff like this. What other stuff would you like to see with this? Running :: To run the examples, one needs a standard Haskell compiler with ffi (ghc) and fltk installed (http://www.fltk.org). run make. If necessary, change the makefile to modify for your configuration. f_*_stub.cpp -- These are the stubs that are used to bind the c++ library to c functions. This is required because the Haskell ffi standard does not specify any conventions for C++. Fl.hs Box.hs Button.hs Window.hs -- These contain the bindings to the stub files. They also provide a low-level interface for the GUI toolkit. Test_lowlevel.hs -- This is a simple program demonstrating use of the low-level binding. Attributes.hs -- This code was taken from the htoolkit cvs server. Simple modifications were made to suit our purposes. A_Button.hs -- This is an abstraction over the low-level Button interface. It uses the Attributes module for the mid-level interface. Test_midlevel.hs -- This is the same simple program as Test_lowlevel.hs except it uses A_Button instead of Button to demonstrate use of the Attributes abstraction. Cheers, David J. Sankel