[Haskell-cafe] casting numerical types
fis at wiwi.hu-berlin.de
Sat Apr 1 13:11:05 EST 2006
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?
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