patch applied (/haskell/ghc): Add 6.8.1 download page

[Simon Marlow]

Simon Peyton-Jones wrote:
> | 1 the () defaulting in ghci looks highly dubious to me;
> |     having an 'instance Num ()', as given in the doc example,
> |     means that all arithmetic will fail, suggesting that this hack
> |     is far too intrusive:
> |
> |         *Main> 1+2
> |         *** Exception: def.hs:1:0: No instance nor default
> |                 method for class operation GHC.Num.+
> |
> |     instead of meddling with a wide-ranging and subtle
> |     feature like defaults, wouldn't it be easier to switch
> |     off ghci's printing of io-results? or use the old standby
> |
> |         void m = m >> return ()
> 
> Well perhaps. But I think all the other alternatives (that I know of) have their own disadvantages.  E.g. I'm sure we'd get complaints if we did something wide ranging like switching off the printing of IO-results.
> 
> The current system has the advantage that it's almost always just what you want, but the disadvantage that it will behave oddly in very obscure circumstances (when you define instance Num ()).  So we just documented the obscure behaviour.  Let's see if it bites anyone.

I think that -fno-print-bind-result should be the default.  Several people 
have asked for this, indeed I'm not sure why we didn't make it the default 
when we added the option:

http://hackage.haskell.org/trac/ghc/ticket/887

Cheers,
	Simon