[Hs-Generics] Re: Syb Renovations? Issues with Data.Generics

[Claus Reinke]

Some of you already know, but it seems I forgot to mention this here -
my code has moved to a darcs repo, with a little bit of documentation
and a README summarizing the issues. See my toolbox for more info:

    http://www.cs.kent.ac.uk/~cr3/toolbox/haskell/#syb-utils

Neil: 

It turned out to be tricky to recognize nested types at the
Data/Typeable level, let alone nested types that really have 
an infinite set of potential substructure types (which are the
ones that break the PlateData optimization).

Instead, I just count nesting levels (where nesting means that
we encounter the top-level type constructor while exploring
its substructure types), and set an arbitrary bound beyond
which I assume the nesting to be recursive and fall back to
the unoptimized case.

You might want to apply something similar to PlateData.

Cheers,
Claus