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 [EMAIL PROTECTED] 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.) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Why does the class called Real support only rationals, and not all reals?
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. Here's one proposal for a small step in the right direction: http://hackage.haskell.org/trac/haskell-prime/ticket/112 But it really needs a mathematician to sit down and sort it out properly. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Why does the class called Real support only rationals, and not all reals?
On 6/4/07, DavidA [EMAIL PROTECTED] 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! -- Dan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
