Records in Haskell

[Wolfgang Jeltsch]

Am Montag, den 07.11.2011, 23:30 +0000 schrieb Simon Peyton-Jones:
> Wolfgang
> 
> Is there a wiki page giving a specific, concrete design for the
> proposal you advocate?  Something at the level of detail of
> http://hackage.haskell.org/trac/ghc/wiki/Records/OverloadedRecordFields?

Well, I don’t propose a new record system as a language feature.
Instead, I’ve implemented a record system as a library. The paper at

    <http://www.informatik.tu-cottbus.de/~jeltsch/research/ppdp-2010-paper.pdf>

describes this in detail, and the records package at

    <http://hackage.haskell.org/package/records>

is the actual library.

My stance is that it is possibly better if we do not try to include a
one-size-fits-it-all record system into the language, but if the
language provided support for basic things that almost all record system
*libraries* would need. In my opinion, there is at least one such thing
that should get language support: field labels. There is already the
proposal at

    <http://hackage.haskell.org/trac/haskell-prime/wiki/FirstClassLabels>

for first-class field labels.

> I am unsure whether you regard it as an alternative to the above, or
> something that should be done as well.   And if the former, how does
> it relate to the challenge articulated on
> http://hackage.haskell.org/trac/ghc/wiki/Records, namely how to make
> Haskell's existing named-field system work better?

I don’t think that everyone should use my record system. I see it as one
member of a family of reasonable record systems.

My intention, when developing my record system, was not to make the
existing system better, since I needed quite a lot of advanced features
that anything near Haskell’s existing record system couldn’t give me. So
I started something completely new.

> Thanks
> 
> Simon

Best wishes,
Wolfgang