Re: [Haskell-cafe] Abstraction in data types

Only one small nit here: On Mar 18, 2010, at 09:58 , Tillmann Rendel wrote:

And we express Point as a GADT using Spherical and Cartesian as follows.

data Point i = Cartesian :: Cartesian_coord -> Cartesian_coord -> Point Cartesian | Spherical :: Latitude -> Longitude -> Point Spherical

The actual syntax for this is

data Point i where Cartesian :: Cartesian_coord -> Cartesian_coord -> Point Cartesian Spherical :: Latitude -> Longitude -> Point Spherical

-- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allbery@kf8nh.com system administrator [openafs,heimdal,too many hats] allbery@ece.cmu.edu electrical and computer engineering, carnegie mellon university KF8NH