Comments on current TypeHoles implementation

[Roman Cheplyaka]

* Roman Cheplyaka <roma at ro-che.info> [2012-10-05 10:22:23+0300]
> * Simon Peyton-Jones <simonpj at microsoft.com> [2012-10-05 07:14:36+0000]
> > | Sounds cool. I would also expect that if you have several occurences of
> > | the same unbound identifier, then it gets a unified type.
> > 
> > I thought about this, but I think not. Consider
> > 
> > f x1 = _y
> > g x2 = _y
> > 
> > Do you want _y and _y to be unified, so that f and g are no longer polymorphic?  I think not.  Any more than the "_" holes we have now are unified.
> 
> Do you mean polymorphism in their argument? Why would it go away?
> 
> I would expect the functions to get types `a -> c` and `b -> c`
> respectively, and `c` to be reported as the type of the hole.

Ah, I see. Since `c` is universally quantified, it means different
things for f and g. Good point.

Roman