Am Montag, 21. November 2005 14:27 schrieb 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
As I pointed out in another e-mail just sent, this kind of special syntax only solves a very specific problem so that it's questionable whether this syntax should be included into Haskell. However, if we manage to create a more generalized approach, inclusion of it into the language might be quite fine. In addition, having a line which begins with "data" declaring a class is *very* misleading, in my opinion.
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Best wishes, Wolfgang