[Haskell] Re: sizeFM type

[Serge D. Mechveliani]

On Mon, Apr 26, 2004 at 10:09:18PM +0200, Ketil Malde wrote:
> "Serge D. Mechveliani" <mechvel at botik.ru> writes:
> 
> > Alexander is right.
> > 
> > Also as  Integer  has more sense than  Int,
> > I would suggest for the future standard Haskell library to have  
> > Integer as default. For example:
> >                                 length      :: [a] -> Integer
> >                                 smallLength :: [a] -> Int
> 
> Hmm...isn't it possible to use a class here?  Perhaps even Num?
> 
>     class Num a where ....
>         :
>         length :: [b] -> a
>         :
> 

I think, for many functions, like  length,  it is most natural to 
return  Integer  only.  
And it is also natural for many instances (domains) D to provide 
maps like  toInteger, fromInteger.
Just follow mathematics.

Example:           length xs                :: (Rational, Rational)  
looks unnatural,
but                fromInteger (length xs)  :: (Rational, Rational)  
looks natural.

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