instance overaps with lib

Serge D. Mechveliani mechvel at botik.ru
Tue Sep 5 04:50:39 EDT 2006


More about instance overlaps with the GHC library:

I need to print in a special way the data of
[Equation], (Term, Term), [(Term, Term)], (Equation, Equation).

The first can be by defining  showList  in  instance Show Equation.
But  Show  has not a method of  showPair. So, I need to write the 
function  showsTermPair  and to use it together with another home-made 
function  showsListGeneric.

And in  ghc-6.4.1,  it was sufficient to define the instances and to use 
only `shows'.

About prompt feed-backs from users:
this issue of possible fisfeature with overlaps does not look tragic. 
But with the  Map  library for Haskell-98, I take it as a considerable 
loss. It was said that I had a chance to make it standard, if asked about 
it in time.

-----------------
Serge Mechveliani
mechvel at botik.ru





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