Mark Tullsen wrote:
> Matt Harden wrote:
> > o A Zippable class be created, defining zip and unzip for all tuple
> > types (or at least the first few)
>
> For _all_ tuple types? That's a lot of instance declarations ;-)!
No doubt. But seriously, I was thinking of a "built-in" Zippable
instance just like we have for Ord, Enum, Show, etc. I think the
language definition specifies these instances for all tuple types that
have sensible instances of these classes. Actual Haskell
implementations don't provide these instances for all tuples, AFAIK.
> <shameless plug>
>
> I have a paper ("The Zip Calculus", MPC 2000) which is a bit more
> ambitious, and is correspondingly more complex. My solution allows
> one to write the generic zip without use of the class system and
> the theoretic need for an infinite number of instance declarations.
> It allows you to write transpose
> transpose :: ((a,b),(c,d),(e,f)) -> ((a,c,e),(b,d,f))
> generically for any m*n "matrix".
>
> I hope to write up a proposal for how to add this capability to Haskell
> in the not too distant future.
>
> You can get the paper here if you're interested:
> http://cs-www.cs.yale.edu/~tullsen/zip-mpc.ps
I have lots of questions, but I'll wait until I've read your paper.
Thanks!
Matt Harden
