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?
Cheers,
Greg
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
http://research.microsoft.com/en-us/um/people/crusso/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
http://hackage.haskell.org/trac/ghc/ticket/4295
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!
Thanks
Simon
| -----Original Message-----
| From: haskell-cafe-boun...@haskell.org
[mailto:haskell-cafe-boun...@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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| Haskell-Cafe mailing list
| Haskell-Cafe@haskell.org
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