[Haskell-cafe] Which generic zipper?

Roman Cheplyaka roma at ro-che.info
Thu Apr 11 08:24:12 CEST 2013

Note that syz is essentially based on Data.Data, which is no less
"official" than GHC.Generics. (The compiler can derive Data with

I am not sure what your primary concern is. In case you are concerned
with the ease of deriving generic instances, almost every generics
library out there, including traverse-with-class, provides a TH function
for deriving the necessary instances.

You can write a zipper based on GHC.Generics, but it won't be a
straightforward translation of syz (nor would it be a trivial


* Luke Evans <luke at eversosoft.com> [2013-04-10 16:38:17-0700]
> Hmm, in my naivety I failed to notice that the 'official' GHC.Generics
> are completely different to SYB on which syz is built.  Classic case
> of reading the same words/names and assuming they're exactly the same
> thing.
> Maybe it's not that hard to rewrite syz in terms of
> GHC.Generics.Generic (I'll perhaps take a look), but maybe there's a
> generic Zipper library already based on the GHC stuff?  
> On 2013-04-10, at 3:19 PM, Roman Cheplyaka <roma at ro-che.info> wrote:
> > ...Apart from that, I am not aware of any problems with syz.
> > 
> > Roman

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