[Haskell-cafe] casting numerical types

hi all, this should be a quick one (for now I would be happy with a "that's impossible", just want to make sure I don't miss anything). I want to compute the average from a list of arbitrary numerical element type. I wanted to do this: avg :: (Num a) => [a] -> a avg xs = sum (map fromNum xs) / (fromIntegral (length xs)) but it doesn't compile. All I could get to work is this: avg :: (Fractional a) => [a] -> a avg xs = sum xs / (fromIntegral (length xs)) avgI :: (Integral a) => [a] -> Float avgI = avg . map fromIntegral The two function names for the same thing are tolerable, but not very elegant. Is there another option? Thanks, Matthias