darcs patch: implement prefix unboxed tuples syntax (#1509)

[Simon Marlow]

Isaac Dupree wrote:
> attached are patches for ghc and for testsuite.  They seem pretty 
> straightforward.  Adding prefix-unboxed-tuples turned out to just 
> require a parser modification -- ( contrary to a comment in 
> http://hackage.haskell.org/trac/ghc/ticket/1509 ) for GHC at least, 
> Data.Tuple only defines data types and constructors (and Eq,Ord... 
> instances) of (boxed) tuples; unboxed tuples were already built-in, (or 
> anyway my test passed and ran successfully after a simple parser 
> addition). --should the test be in should_run instead of should_compile, 
> because it is runnable and I did manually test running it, or not 
> because it would just waste test-running time now that I've seen once 
> that it can run, and it being mostly a parser test, backed up by 
> typechecking?
> 
> proposed review deadline: 12 January (I'm pretty confident that these 
> changes are correct)
> 
> P.S. HEAD's ./validate has had some testsuite errors for a while

Looks good to me, I have no objections to your committing it.

Cheers,
	Simon