(/) operates on a Fractional instance... but length returns an Int, which is
not a Fractional.
You can convert the Int to a Fractional instance:
mean xs = sum xs / fromIntegral (length xs)
or try an integer division:
mean xs = sum xs `div` length xs
-n
On Thu, Jun 30, 2011 at 10:55 PM, Ruohao Li
Hi guys,
I just started learning some Haskell. I want to implement a mean function to compute the mean of a list. The signature of the function is: mean :: (Num a, Fractional b) => [a] -> b But when I implement this simple function, the compiler keep whining at me on type errors. I know this is wrong: mean xs = sum xs / length xs But how to get it right? Thanks.
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