two easy questions

[Hal Daume III]

succ Blue cannot return MrX unless Blue and MrX have the same type.  What
I meant was that you would say:

  'succ (Detective Red)'   ==> Detective Green
  'succ (Detective Green)' ==> Detective Blue
  'succ (Detective Blue)'  ==> Fugitive MrX

--
Hal Daume III

 "Computer science is no more about computers    | hdaume@isi.edu
  than astronomy is about telescopes." -Dijkstra | www.isi.edu/~hdaume

On Thu, 20 Feb 2003, Mike T. Machenry wrote:

> I tried this. It doesn't work. succ Blue is an exception. Anybody else know
> how this should be done?
> 
> Thanks,
> -mike
> 
> On Thu, Feb 20, 2003 at 08:00:04AM -0800, Hal Daume III wrote:
> > > Question 1: Is there an easier, more elegant way to write this code?
> > 
> > For the most part, no.
> > 
> > > Question 2: Is there a way to express the following relationship?
> > >  I want to have a set of symbols with ordering and another set that is
> > > part of that ordering but with a different parent. For exammple,
> > > 
> > > data Player = Detective | Fugitive deriving (Enum)
> > > data Detective = Red | Green | Blue deriving (Enum)
> > > data Fugitive = MrX deriving (Enum)
> > 
> > How about something like:
> > 
> > > data Player = Detective Detective | Fugitive Fugitive deriving (Enum)
> > > data Detective = Red | Green | Blue deriving (Enum)
> > > data Fugitive  = MrX deriving (Enum)
> > 
> > (I'm not sure if the deriving Enum on Player will be exactly what you want
> > -- I think so though.  I don't derive this class very often.)
> > 
> > Then you can test detectiveness by:
> > 
> > > isDetective (Detective _) = True
> > > isDetective _             = False
> > 
> > HTH
> > 
> >  - Hal
> > 
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