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

On Apr 3, 2008, at 10:41 AM, Luke Palmer wrote:

On Thu, Apr 3, 2008 at 9:58 AM, Ben Lippmeier

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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-1039-0... Aaron