[Haskell-cafe] Impredicative Types
gcross at phys.washington.edu
Fri Nov 19 14:59:28 EST 2010
Awesome, thank you. :-) One more question out of pure curiosity, if
you have the time: What is allowing you to keep them in? I thought
that the problem was that they made a mess that touched every party of
the type checker rather than being centralized in one place. Was there
a trick you discovered that now allows you to support them without
creating such a mess?
On 11/19/10 11:45 AM, Simon Peyton-Jones wrote:
> Yes, impredicative types are still in, but in a simpler form than before, along the lines of QML
> I have been too busy with getting the new type checker working to describe or document it. Notably, I have not yet added syntax for QML's rigid type annotations, which leads to a loss of expressive power.
> too much to do!
> Bottom line: if you are interested in impredicative polymorphism, let me know. A good way to do so would be to register your interest on
> Just add your email address to the cc list, *and* write a comment giving an example of how you are using impredicative poly, and pointing to any further info. That'll help motivate me to do the remaining work!
> | -----Original Message-----
> | From: haskell-cafe-bounces at haskell.org [mailto:haskell-cafe-bounces at haskell.org]
> | On Behalf Of Gregory Crosswhite
> | Sent: 19 November 2010 19:23
> | To: Haskell Cafe
> | Subject: [Haskell-cafe] Impredicative Types
> | Hey everyone! I haven't had a chance to try out GHC 7 myself, but I saw
> | in the documentation that Impredicative Types are still supported. Is
> | this true? I thought that they were on their way out because they
> | overcomplicated type checking; has this plan been changed?
> | Cheers,
> | Greg
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