On 10/9/07, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > So, you assume that acos should have a *default* implementation in the > Floating class? Propose it, please.
I don't think the proposal makes any such assumption. It implies only that *if* you provide acos, pi will be provided for you automatically if you want. > Note, BTW that from the viewpoint of "actual" correctness, it would be > better to have PI as exact as possible, while acos, well, it is a trans- > cendental function, whose representations are usually approximate... pi is a transcendental number, same argument applies. I wouldn't want pi defined in terms of a transcendental function because people often use the Num type class to represent things that aren't actually numbers, eg. power series or ASTs for an embedded language. The reusability of Num varies inversely with how many assumptions you make about it. -- Dan _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
