dependingOn in 6.6

[Simon Marlow]

John Meacham wrote:
> I was wondering if we could be sure to get
> 
> dependingOn :: a -> b -> a
> dependingOn = ....
> 
> in ghc 6.6? this has been discussed before, it is implemented in jhc and
> I have found all sorts of use for it as it can be used to control let
> floating and inlining in a nice general way and is trivial to implement.
> (one for ghc was posted before based on primitives it already
> implements)
> 
> we just need to decide on a module to export it. 
> 
> the meaning is that 
> 
> x = ... `dependingOn` y
> 
> returns x with an artificial dependency on y. so things using x cannot
> be floated out above where y is defined.

If you make a ticket for it, we can try to get to it for 6.6, but it's probably 
unlikely at this stage.

It's like the touch# primitive we already have, but I'm not sure if it can be 
implemented using touch#.  We did discuss this before, IIRC - do you have a 
pointer to the discussion?

Cheers,
	Simon