在 Haskell 中计算 3 和 5 的倍数之和时出现内存不足错误

Question

This is my code:

import Data.Bits

main = print . sum . takeWhile( < 200000) $ multSum 999

multSum m = 3 : multiples [6..m]  where
    multiples (p:xs) 
       | ((p `mod` 3 == 0)  || (p `mod` 5 == 0)) = p : multiples([p..m])
       | otherwise = p : xs

Error: out of memory (requested 1048576 bytes)

Where am I going wrong?

Answer 1

multSum isn't doing what you think it is. Try debugging it directly:

*Main> take 20 $ multSum 999
[3,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6]

Answer 2

multSum为所有参数返回无限列表[3,6,6,6,6...] ，因此它永远不会超过 200000，因此无法打印您请求的总和。

Answer 3

try

mults35 m = multiples [3..m] .....
  ............
  ....| ......    = p : multiples xs
  ... | otherwise =     multiples xs

there will be one more thing for you to add there. Try this, and you'll see.