指数默认为整数 [英] Exponents defaulting to Integer

问题描述

我使用（^）::（Num a，Integral b）=> a - > b - >一个很多来定义常数因子或大小。问题是，GHC抱怨默认为整数。

现在我知道为什么会发生这种情况......而且我知道我可以写（x ^（y :: Int））来摆脱警告。但那看起来很丑陋。

同样的事情适用于（^^）::（积分b，分数a） => a - > b - > a 和（**）:: Floating a => a - > a - >

任何人都可以很好地解决这个（第一个世界）问题吗？

edit

刚刚发现了这段代码：

  align a = 2 ^ ceiling（logBase 2（fromIntegral（sizeOf a）））
  

这是一个LOC，GHC抱怨在同一行上违约为整数和 Double 。

解决方案

你可以用更具体的类型定义你自己的操作符。或者你可以使用更具体的类型来重新定义（^）运算符，如下所示：

 < $（^））
 $ b $（^）:: Num a => code> import Prelude hiding（（^））
 import qualified Prelude a  - > Int  - > a 
（^）=（Prelude。^）
 
x :: Int 
x = 2 ^ 3 
  

I use (^) :: (Num a, Integral b) => a -> b -> a a lot to define constant factors or sizes. Problem is that GHC complains about defaulting to Integer.

Now I know why this happens ... and I know that I can "just" write (x^(y::Int)) to get rid of the warning. But that looks just "ugly". Otoh living with the warnings is also not a great option.

Same thing applies for (^^) :: (Integral b, Fractional a) => a -> b -> a and (**) :: Floating a => a -> a -> a is not usable to me.

Anyone has a nice solution to this (first world) problem?

edit

Just found this gem of code:

alignment a = 2 ^ ceiling (logBase 2 (fromIntegral (sizeOf a)))

This is one LOC and GHC complains about defaulting to Integer and Double on the same line.

解决方案

You could define your own operator with a more specific type. Or you could redefine the (^) operator with a more specific type, like this:

import Prelude hiding ((^))
import qualified Prelude ((^))

(^) :: Num a => a -> Int -> a
(^) = (Prelude.^)

x :: Int
x = 2^3

这篇关于指数默认为整数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！