How would one implement a list of prime numbers in Haskell so that they could be retrieved lazily?
I am new to Haskell, and would like to learn about practical uses of the lazy evaluation functionality.
4 Answers
primes = 2 : [x | x <- [3..], all (\y -> x `mod` y /= 0)
(takeWhile (<= (floor . sqrt $ fromIntegral x)) primes)]
With 2 in the list initially, for each integer x greater than 2, check if for all y in primes such that y <= sqrt(x), x mod y != 0 holds, which means x has no other factors except 1 and itself.
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