[Haskell-cafe] Typing with co/contra-variance.

[Aaron Tomb]

On Apr 3, 2008, at 10:41 AM, Luke Palmer wrote:
> On Thu, Apr 3, 2008 at 9:58 AM, Ben Lippmeier <Ben.Lippmeier at anu.edu.au 
> > wrote:
>> Questions:
>> 1) Could I perhaps wave my arms around and say something about the  
>> Int in
>> the type of isEven being in a  contra-variant position? Is this  
>> what is
>> actually happening?, and can someone point me to a good paper?
>
> This is related to "gradual typing".  I don't know how much work has
> been done into inference for gradual typing, but I'll bet you could
> hack on the HM algorithm a little and get something usable.
>
> Here's a relevant paper:
> http://www.cs.colorado.edu/~siek/pubs/pubs/2006/siek06:_gradual.pdf


Yeah, there is work on inference for gradual types:

http://www.cs.colorado.edu/department/publications/reports/docs/CU-CS-1039-08.pdf

Aaron