[Haskell-cafe] Abstraction in data types

[Brandon S. Allbery KF8NH]

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 at kf8nh.com
system administrator [openafs,heimdal,too many hats] allbery at ece.cmu.edu
electrical and computer engineering, carnegie mellon university    KF8NH


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