darcs patch: Add equating p x y = p x == p y

[Simon Marlow]

Malcolm Wallace wrote:

> I would like to propose a new module for functions like this, which are
> in some sense "purely" functional, that is, they do not involve any data
> structure at all, just functions.  Other examples would be
> 
>     const
>     id
>     flip
>     (.)
>     ($)
>     ($!)
> 
> Any suggestions for a good name for such a module?  Data.Function does
> not sound right to my ears.

Clearly, they should all go in a module called Util.  Or possibly 
GeneralUtilities ;-)

Seriously, currently they are all provided by Prelude, and lacking an obvious 
separate place to put them, I think Prelude is just fine.  The reasons to put 
them somewhere else would be if the list grew longer and/or there were some that 
we didn't want in scope by default; but I don't see either of these being the 
case soon.

Cheers,
	Simon