Re: [Haskell-cafe] Re: Why purely in haskell?

Am Freitag, 11. Januar 2008 10:54 schrieb Wilhelm B. Kloke:

Wolfgang Jeltsch schrieb:

...

However, the fact that (0 / 0) == (0 / 0) yields False is quite shocking. It doesn?t adhere to any meaningful axiom set for Eq. So I think that this behavior should be changed. Think of a set implementation which uses (==) to compare set elements for equality. The NaN behavior would break this implementation since it would allow for sets which contain NaN multiple times.

You forget, that the intention of NaN is denial of membership of any set of numbers.

This doesn’t matter. The Set data type I’m talking about would not know about NaN and would therefore allow multiple NaNs in a set. Best wishes, Wolfgang