[Haskell-cafe] Re: Generic types

Adde adde at trialcode.com
Tue Jun 14 03:27:36 EDT 2005

While we're at it, I tried adding a class Length in between Unit and Meter, like

class Unit u where
    shortName :: u -> String

class (Unit u) => Length u

instance Length Meter where
    shortName u = "m"

>From the information I can find on the web subclassing should include all
of the methods in the superclasses but I get this error:

`shortName' is not a (visible) method of class `Length'

More information about the Haskell-Cafe mailing list