Funções básicas de estatística implementados em Haskell

statistics.hs

import Data.List

media :: Fractional a => [a] -> a
media l= let (t,n) = foldl' (\(!b,!c) a -> (a+b,c+1)) (0,0) l in t / n

desvios :: Fractional a => [a] -> a -> [a]
desvios xs m = [ a - m | a <- xs ]

powtwo :: Fractional a => [a] -> [a]
powtwo xs = [ a ^ 2 | a <- xs ]

variancia :: Fractional a => [a] -> a
variancia xs = sum (powtwo (desvios xs (media xs))) / realToFrac(length xs - 1)

desvioPadrao :: Floating a => [a] -> a
desvioPadrao xs = sqrt (variancia xs)