[Int]的总和导致溢出 [英] Sum of [Int] causes overflow

问题描述

我有一个返回[Int]的函数，我想取列表的总和.但是，尽管每个元素都小于maxBound::Int，但总和肯定更大.

I have a function that returns [Int] and I would like to take the sum of the list. However, while each individual element is smaller than maxBound::Int, the sum is definitely larger.

(人为)示例:

ghci> sum ([1..10000000] :: [Int])
-2004260032

是否有任何方法可以迫使总和累积到Integer而不是Int中?我在想这个错误吗?

Is there any way to force sum to accumulate into an Integer instead of an Int? Am I thinking about this wrong?

推荐答案

sum返回与其输入列表元素相同的类型:

sum returns the same type as its input list elements:

sum :: Num a => [a] -> a

，因此您需要将其传递给[Integer]才能返回Integer.如果您的输入列表已经是[Int]类型，则可以使用以下功能:

so you need to pass it a [Integer] in order to return an Integer. If your input list is already of type [Int], you can use the function:

sum . map fromIntegral

相反:

ghci> sum . map fromIntegral $ ([1..10000000] :: [Int])
50000005000000

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