[Haskell-cafe] Serialising types with existential data constructors

[Misha Aizatulin]

> Klaus Ostermann and I allude to this non-trivial extensibility problem 
> in our GPCE 2006 paper
> and we started to look into ways (not in that paper) to resolve
> the problem in a principled way.

  I'm really looking forward to that! For now I'll probably use Template
Haskell to register all instances that have to be serialized and output
the mapping head->type in the end.

Cheers,
  Misha