> The report says explicit that instance declarations like
> instance C (a,a) where ..., or for (Int,a) or for [[a]] are not
> I now only would like to know why this design decission was made,
> are there any problems with the instance declarations I have in mind?
You might find "Type classes - exploring the design space" useful.
http://www.dcs.gla.ac.uk/~simonpj/multi.ps.gz
Simon
