[Haskell-cafe] Re: pi

[ok]

Someone wrote about pi:

| But it is just a numerical constant, no need to put it into a  
class, and
>> nothing to do with the type_classing of related functions. "e" is not
>> std. defined, and it doesn't kill people who use exponentials.

But it *isn't* "A" numerical constant.
It is a *different* constant for each instance of Floating.
In this respect, it's not unlike floatRange, which is just "a"
constant (a pair of integers), but is different for each
RealFloat instance.