updating labelled fields

[John Meacham]

DrIFT which i am now maintaining can derive such utility functions out
of the box. just add a {-!deriving: update -} to get update functions
for every labeled field in a datatype. quite useful, I have not updated
the web page yet, but the new DrIFT homepage will be at

http://homer.netmar.com/~john/computer/haskell/DrIFT/

On Mon, May 06, 2002 at 07:36:30PM +0100, Jorge Adriano wrote:
> Anyway I'd prefer to have some way to 'derive' apply and set functions.
> Something like 
> > data MyData = MyData { foo :: fooType, bar :: ..., .... }
> >  deriving (Set, Apply)
> 
> Using the keyword "deriving" would probably be a bad idea though :)
> The set and apply functions could be derived with a standard postfix or maybe 
> prefix... fooAp or apFoo.
> Maybe we could introduce sintax to specify it...
> > deriving (Set with "set", Apply with "ap")
> 
> I don't know... I'm just brainstorming right now.
> Having actual functions is important. I don't think I have to explain why to 
> people in this mailing list :-)
> 
> > Anyway, does such a thing exist, and, if not, is there any chance it could
> > exist, or is it just syntactic salt to too many people? :)
> I whish you better luck than I've had so far whenever making posts about this 
> same issue ;)
> 

-- 
---------------------------------------------------------------------------
John Meacham - California Institute of Technology, Alum. - john@foo.net
---------------------------------------------------------------------------