Survival of generic-classes in ghc

[Simon Peyton-Jones]

| As long as we're reifying everything in sight, why not=20
| simplify the design problem and reify the constructor dictionaries?

Because the generic function may be building the contructor
not taking it apart.  (Think of a generic read function).  So there
is no reified constructor to deconstruct.  This is discussed in the
generic classes paper.  It has to be done by recursion over the type.
It's emphatically not just an efficiency issue.

Simon