Dear Haskellians,
A new C9 video in the series!
So, you folks already know most of this... except for maybe the
generalization of the Conway construction!
Best wishes,
--greg
-- Forwarded message --
From: Charles Torre ...
Date: Tue, Jul 26, 2011 at 1:12 PM
Subject: C9 video
On 27 July 2011 10:31, Greg Meredith lgreg.mered...@biosimilarity.com wrote:
Dear Haskellians,
A new C9 video in the series!
So, you folks already know most of this... except for maybe the
generalization of the Conway construction!
Best wishes,
--greg
Thanks for the heads up! I love these
I'm always glad to see videos like this. I wish more people could have that
much fun playing with math ;).
It wouldn't really be suitable for your application but another interesting
generalization is to insert the 'Either' at the top level:
data ConwayT m a
= Pure a
| ConwayT
For any who are interested, here's a quick and dirty Haskell version of the
generalized Conway game monad transformer described in the video. It uses two
newtypes, L and R, to select from two possible implementations of the Monad
class.
(all the LANGUAGE pragmas are just to support a derived
Dang, I should have played with both versions before sending this. The 'R'
instance has a very obvious error:
return x = R (ConwayT (return (Left x)) mzero)
should be changed to
return x = R (ConwayT mzero (return (Left x)))
Sorry!
-- James
On Jul 27, 2011, at 9:28 AM, James Cook
Dear James,
This is so cool! It's so natural to express this as a monad transformer.
It's great insight and it's just the sort of insight that Haskell and this
way of thinking about computation makes possible. Bravo!
Best wishes,
--greg
On Wed, Jul 27, 2011 at 6:33 AM, James Cook
