instance overlap in 6.6 candidate

[Chris Kuklewicz]

Simon Peyton-Jones wrote:
> | ------------------------------------------------
> | data Equation = ...
> | instance Show Equation where ...
> | 
> | instance Show [Equation]
> |   where
> |   showsPrec _ eqs =  <certain program which prints a list of equation
> |                       in a `nicer' way than by the default list
> printing
> |                      >
> | ------------------------------------------------
> | 
> | This gives the user possibility to redefine a certain part of the
> | library instance.
> | Is not  ghc-6.4.1  better at this point?
> 
> Perhaps.  That's what I'd like feedback about.  What do others think?
> (Incidentally, 6.5 has been like this for about a year without
> complaints.  Also I made the change because people wanted to be able to
> *use* overlapping instances (defined in a library) without having to
> give the -fallow-overlapping-instances flag.)
> 
> Simon

Could overlapping instances be broken into two flags, once with each of the 
desired semantics?


-- 
Chris