As if from nowhere, e appears, at it's own pace!

Inspired by this lovely blogpost I decided to write my own slow and arcane "e" maker. Please compile it before running, otherwise it has runtime complexity O(forever).

	import System.Random
	main = print e
	e :: Double
	e = (+1).average $ map (length . takeWhile (<1) . scanl1 (+) . randomReals) [1..1000000]
	where
	average :: [Int] -> Double
	average x = fromIntegral (sum x) / fromIntegral (length x) -- This is a rubbish (slow) way to average
	randomReals :: Int -> [Double]
	randomReals = randomRs (0.0,1) . mkStdGen more than 500000 takes a while
	-- This generates a random seed from each number and then makes a list of values in(0,1)

view raw slow slow e.hs hosted with ❤ by GitHub

Fast enough and fancy primes oneliner

primes = 2: filter(\x->not$any (\y->mod x y==0) (takeWhile (<(ceiling.sqrt$fromIntegral x+1)) primes)) [3..]

view raw niceprimes.hs hosted with ❤ by GitHub