Generics and dynamics

GOAL:
conversion of unknown types

DISADVANTAGES:
- generic representation consumes lot of disk space.
- conversion typically takes place once.
- (small) parts might be converted

PROPOSAL:
- associate with each type which occurs in a dynamic
  a function which converts it to the generic 
  representation.

  Then the programmer specifies a so-called conversion
  function.

  Finally the result of the conversion function which is
  a generic representation is converted back into a
  'normal' object (if succeeeds)