for review: allow `any' insts as non-local vars in higher-order terms

[Fergus Henderson]

On 17-Feb-1998, Peter Schachte <pets at students.cs.mu.OZ.AU> wrote:
> > 	In the long term we ought to look at adding support for
> > 	some kind of `any -> the_same_any' mode which is like
> > 	`any -> any' but which does not allow the argument to be
> > 	bound.
> 
> FYI, HAL has this feature.  They use the name `unchanged,' and the idea is
> that the value will not be any more constrained on exit than it was on call.
> That does seem to be what is wanted here.  It's also easy enough to extend
> it to cover free -> unchanged and bound(...) -> unchanged which are synonyms
> for free -> free and bound(...) -> bound(...).  It's a bit weird, because
> `unchanged' isn't an inst, but it does seem like a nice idea, if it's not
> too much work. 

To make this work I think you need to do some sharing analysis,
which basically means that it is quite a lot of work.

-- 
Fergus Henderson <fjh at cs.mu.oz.au>   |  "I have always known that the pursuit
WWW: <http://www.cs.mu.oz.au/~fjh>   |  of excellence is a lethal habit"
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