In principle this sounds good.  I just thought I'd mention

  http://hackage.haskell.org/trac/ghc/ticket/3355

which is related, though not directly.

Cheers,
        Simon

On 15/09/2012 09:32, Simon Peyton-Jones wrote:
Niklas

Yesterday we discussed the possibility of merging your haskell-src-exts
and the template-haskell library, as part of your vision for a Haskell
Suite.

**

*Motivation*.  It’s stupid, stupid to have both the *large*
Language.Haskell.TH data types for Haskell and the *large*
Language.Haskell.Exts data types for Haskell.

·The duplication does not serve our users well.  Sometimes they even
need to grapple with BOTH data types in the same probram, and We even
have a package that converts from one to the other!

·The duplication does not serve use as developers well. We are
duplicating some pretty serious effort on data type design, pretty
printer, analysis, etc etc.

*Proposal*.

·We merge the two

·You remain the primary maintainer

·The new package (however we name it) completely replaces the existing
template-haskell package.

All this relies on a clear sense that you, and other friends who help
with haskell-src-exts, will continue to love, maintain, and develop it.
Of course, there is a virtuous cycle here: sustaining that energy will
become easier if it was central to Template Haskell.  But I would NOT
want people to feel “Oh, now haskell-src-exts is part of GHC, so we
don’t need to continue to love and maintain it”.

*Issues*

·There are a few bits in the TH data type that specifically support
Template Haskell, including

oThe Name type (reconciliation needed here)

oThe Q monad and result types for reify (no equivalent in haskell-src-exts)

I think we can solve all this with some negotiation, but I guess it is
just possible that there is some major technical obstacle.

·The massive question is the disruptive effect on existing TH users.
Changing all the data types will be a Real Pain for them.  But the long
term benefits seem quite compelling.  We’d need to make a clear blog
post/email etc to advertise and seek feedback.

One possibility is to support BOTH for a while (deprecating the existing
data types).  Perhaps by having two package (old and new). Initially
“old” is deprecated but is the package you get by default.  But “new” is
available, and the same GHC can deal with its data types.  I think this
would be possible, with some work.

·Who will do the work?  (There will be quite a bit!)  I think you
sounded willing consider taking the lead, though of course you will want
to think more about it before making a commitment.  For my part I am
definitely willing to discuss details, and would want to be involved in
the design decisions, but I can’t commit to doing Serious Work.  So this
only makes sense if, upon reflection, you and whatever friends you can
persuade to join you, are willing to take the lion’s share of the work.

best wishes

Simon



_______________________________________________
Cvs-ghc mailing list
[email protected]
http://www.haskell.org/mailman/listinfo/cvs-ghc



_______________________________________________
Cvs-ghc mailing list
[email protected]
http://www.haskell.org/mailman/listinfo/cvs-ghc

Reply via email to