Re: [Haskell-beginners] Enum for natural numbers

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" An: kane96@gmx.de CC: "Brandon S. Allbery KF8NH" , beginners@haskell.org Betreff: Re: [Haskell-beginners] Enum for natural numbers

On Dec 17, 2009, at 12:21 , kane96@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@kf8nh.com system administrator [openafs,heimdal,too many hats] allbery@ece.cmu.edu electrical and computer engineering, carnegie mellon university KF8NH

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