GADTs in the wild

[Felipe Almeida Lessa]

Christopher, did you ever take a look at acid-state [1]?  It seems to
me that it solves the same problem you have but, instead of

  Client <-> JSON <-> Server (going through the web)

it solves

  Server <-> Storage <-> Server (going through time)

Cheers,

[1] http://hackage.haskell.org/package/acid-state

-- 
Felipe.