[Haskell-cafe] records proposals list

[David Roundy]

On Sun, Nov 20, 2005 at 04:21:05PM +0100, Wolfgang Jeltsch wrote:
> Am Samstag, 19. November 2005 17:35 schrieb Bulat Ziganshin:
> > 7. OOP-like fields inheritance:
> >
> > data Coord = { x,y :: Double }
> > data Point : Coord = { c :: Color }
> >
> > of course this is just another sort of syntax sugar once we start
> > using classes to define getter/setter functions
> 
> I thought that even many OO people say that inheritance of fields is not
> good practice.  So why should we want to support it?

Think of it instead as being syntactic sugar for a class declaration:

class Coord a where
  get_x :: a -> Double
  get_y :: a -> Double
  set_x :: Double -> a -> a
  set_y :: Double -> a -> a

Coord might not be the best example, but I'd certainly like to be able to
automatically derive this sort of class functionality without writing lots
of boiler-plate instances.
-- 
David Roundy
http://www.darcs.net