Re: compare on Double

On Wed, Mar 21, 2007 at 06:58:46PM +0000, David House wrote:

On 21/03/07, Neil Mitchell wrote:

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Following on from the tradition of ByteString, will it be acceptable for the compiler to turn _|_ into False, as an optimisation?

My interpretation of Ian's message was a questioning of the behaviour of compare, not of (<) etc. compare can't return False.

Right, I'm happy with the three False's, it's the incompatible result of compare that I'm objecting to. As Sven thinks the real solution is to modify the report such that this case can be handled nicely without raising an exception, I've closed the proposal and opened a Haskell' ticket for it. Thus we can discuss what the answer should be for Haskell' and change the report or not as we think appropriate, before finally fixing the problem. http://hackage.haskell.org/trac/haskell-prime/ticket/123

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I agree very much with Sven here, nothing as simple as comparison or equality should make a program crash. I wouldn't mind division by zero raising an error - that is something that you could argue for.

Doesn't compare need to force its arguments anyway, so that (0/0) `compare` (0/0) would be a divide-by-zero error?

Not with Float and Double: Prelude> 0/0 :: Double NaN Prelude> 0/0 :: Float NaN Thanks Ian