Tuple-like constructors

[Simon Peyton-Jones]

| There has been a suggestion that the 'deriving' mechanism be
de-coupled
| from the datatype declaration.  Together with a generic default
| definition, that means you could write something like
| 
|     deriving Bin for (,,,,,,,,,,,,,,,,,,,,)
| 
| and hence not need to write the tedious instance header yourself,
| since the compiler can easily infer it.

Yes -- a couple of times I've nearly gotten down to implementing this.
Given that we have the deriving mechanism at all, we might as well make
it a bit more useful.  The only real obstacle is defining a suitable
syntax.  It makes the language bigger, but not in a deep way.   

Simon