Re: [Haskell-cafe] Re: Why does the class called "Real" support only rationals, and not all reals?

On Mon, 4 Jun 2007, Dan Piponi wrote:

On 6/4/07, DavidA wrote:

...

Yes, I'm afraid that you are understanding correctly. Annoying isn't it.

It is well-known (among Haskell mathematicians at least) that the numeric type classes in the prelude are broken.

A few days ago I found myself forced to write:

...

instance Floating Fixed where ...

where 'Fixed' is a fixed point arithmetic class! :-)

When you find yourself having to make a type an instance of the complete 'opposite' class you know you have serious problems!

Indeed. The corresponding class is called Transcendental in NumericPrelude. (And FixedPoint is an instance of it.)