[Haskell-beginners] Enum for natural numbers

[kane96 at gmx.de]

ok, but I shall use Enum in the exercise.


-------- Original-Nachricht --------
> Datum: Thu, 17 Dec 2009 13:56:30 -0500
> Von: "Brandon S. Allbery KF8NH" <allbery at ece.cmu.edu>
> An: kane96 at gmx.de
> CC: "Brandon S. Allbery KF8NH" <allbery at ece.cmu.edu>, beginners at haskell.org
> Betreff: Re: [Haskell-beginners] Enum for natural numbers

> On Dec 17, 2009, at 12:21 , kane96 at gmx.de wrote:
> > toEnum should return Z for negative numbers. I did something like  
> > this but the problem is I don't know how to set "less than". I tried  
> > > and lt:
> >
> > instance Enum Nat where
> >    toEnum (gt 0) = S Z
> >    toEnum (lt 1) = Z
> 
> 
> Take a look at guards.
> 
> -- 
> 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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