[Haskell-cafe] FW: Why does this Ord-class instance crash?

[R J]

Why does the following, trivial  code snippet below hang GHCi when I type"Scalene > Failure", and what's the fix?

data Triangle                  =  Failure                               |  Equilateral                               |  Isosceles                               |  Scalene                               deriving (Eq, Show)
instance Ord Triangle where    Failure     < Failure      = False    Failure     < _            = True
    Equilateral < Failure      = False    Equilateral < Equilateral  = False    Equilateral < _            = True
    Isosceles   < Scalene      = True    Isosceles   < _            = False
    Scalene     < _            = False

(I tried submitting this to beginners at haskell.org, but even though I've signed up for that mailing list, I got a bounce-back saying that I needed admin approval to submit anything to that list, and I haven't heard from an admin, so I'm posting it here.) 		 	   		  
_________________________________________________________________
The New Busy is not the too busy. Combine all your e-mail accounts with Hotmail.
http://www.windowslive.com/campaign/thenewbusy?tile=multiaccount&ocid=PID28326::T:WLMTAGL:ON:WL:en-US:WM_HMP:042010_4
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.haskell.org/pipermail/haskell-cafe/attachments/20100521/9b561dc4/attachment.html