[Hs-Generics] Re: Owning SYB

Neil Mitchell ndmitchell at gmail.com
Mon Jul 28 17:50:10 EDT 2008


>> As you know, Claus has offered a somewhat-detailed proposal for changes to
>> the SYB library (below).  But I don't think that we have an active
>> maintainer for any of the generic-programming libraries (esp SYB) apart from
>> Uniplate.  Then there's the related question of what generic-programming
>> technology to promote for clients of the GHC API.
> Thanks for raising this, Simon. I've actually been holding an email
> summarizing several issues (not just performance of default traversal
> schemes) that I'd like to see adressed in Syb (holding because the Syb
> authors were/are away, and because my performance improvement experiments
> are currently stuck on a
> GHC optimization issue). I'll send that email separately now.

I think SYB would best be maintained by someone who does not already
maintain some kind of boilerplate removal library. There are lots of
experiments into GADT's and other mechanisms, but SYB1+2 is a very
useful design point - and one that should be preserved. I think the
maintainer should do three things in addition to general release

1) Speed improvements, if possible

2) API tweaks, maybe a few extra functions (universe equivalent would be nice)

3) Make it work with Hugs - I've always been surprised that SYB
doesn't work with Hugs, and I don't think its that much work.

As a result of these points, I think Claus is probably the perfect
person to take over as maintainer.

> (a) it helps to have someone else to "blame"
> when the consequences of gfoldl's type once again hurt my brain;-),

You can still blame those that went before - I don't think an SYB
maintainer should be changing the type of gfoldl - its too

> (b) it is really frustrating to get so little interest in these issues,
> well, we haven't even managed to start a proper discussion on any of the
> lists

I am interested. I have starred your emails, and will respond in the
next few days. I've been in a tent without electricity for the last
few days!



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