In practice I would read a file like this:

module Foo where

  myData :: MyData
  myData = MyData {name = "foo",
                   descr = "test"
                   ...
                   }

Reading this into a program is easily feasible with Hint, for example. Then the program would modify some data and serialize it back to:

module Foo where

  myData :: MyData
  myData = MyData {name = "bar",
                   descr = "test2"
                   ...
                   }

In practice I think that the format should be a subset of Haskell that is not Turing-complete.
A bit like JSON, which is a subset of Javascript but not Turing complete.
Is it possible?