> On Thu, Jan 26, 2012 at 8:02 PM, AntC > <anthony_clay...@clear.net.nz> wrote: > > > Ryan Newton <rrnewton <at> gmail.com> writes: > > > > > > > > I admit I'm a big fan of polymorphic extension. But I > > don't love it enough > > for it to impede progress! > > > > Records proposals for Haskell have repeatedly foundered on > the rocks of extensibility. Meanwhile, it seems like > years of experience with field extensibility in OO > languages has shown that it's not an especially good idea, > with authors on programming practice militating for > information hiding instead. > > I don't think it's worth treading that path yet again in > Haskell. > > -Jan
Jan, I agree we shouldn't try leaping forward to extensibility yet. I disagree that we should abandon any thoughts of it and produce a stopgap approach for records that won't ever be extensible. The 'proof of concept' I posted to the list last month http://www.haskell.org/pipermail/glasgow-haskell-users/2011-December/021298.html already includes get and set over polymorphic records and polymorphic fields, I believe, which is half way there. I love Haskell for the way it learns from well-structured mathematical approaches -- in the way I feel OO doesn't. There is a well-structured mathematically sound approach for extensibility, as it happens. It dates back to 1969. It is the 'engine' behind large-scale programming systems all over the world every day. I do and have worked with a lot of them. It's called Relational Algebra, it's based on set theory, it's declarative - which should fit smoothly with Haskell. It has an operation to extend records called 'extend' (!). It has an operation to merge records called 'join'. It has an operation to concatenate records called 'cross-product' You'll probably know it by its 'awkward cousin' SQL. There are many reasons for hating SQL, and there are many reasons why it's a bad fit to OO -- especially because SQL is declarative. There are many reasons to go back to the better-founded mathematical basis that pre-dates SQL. AntC _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users