import Data.List

-- Sieb des Eratosthenes
primes = sieve[2..]
sieve (x:xs) = x: sieve[ y | y <- xs, y `mod` x /= 0 ]

-- Fibonacci-Algorithmus
fib = 0 : 1 : (zipWith (+) fib (tail fib))

-- Permutation
permutations [] = [[]]
permutations xs = [ x:ps | x <- xs , ps <- permutations ( xs\\[x] ) ]