Actually, it is a constant: piDecimalExpansion :: String. A translation from piDecimalExpansion :: String to pi :: Floating a => a is already well defined via read :: Read a => String -> a Any definition of pi in the Floating class that differs from (read piDecimalExpansion) is erroneous. I propose the above as the default definition of pi. Dan Weston ok wrote:
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.
_______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe