如何一般地删除 F# 度量单位 [英] How to generically remove F# Units of measure

问题描述

我有一些数据操作代码，最后会输出 csv.

我开始升级它以在任何地方添加度量单位，但现在我的 csv 函数有问题:

val WriteCSV : string ->'一个列表数组 ->'b 列表 ->字符串 ->单元

(参数为文件名、列数组、列标题、分隔符)

我之前将 [|s;x;y|] 发送到 WriteCSV 的地方，现在遇到了问题，因为我无法发送 [|skm;毫米；嗯|].

我尝试编写一个函数来删除度量单位，但它不起作用.

let removeUnit (n:float<_>) = n/1.0<_>

我的问题是:

• 为什么不起作用?
• 它可以工作吗?
• 还有其他方法可以解决这个特定问题吗?

解决方案

如果我的问题是正确的，将其转换为纯"浮点数会移除单元.例如:

[] type m[<Measure>] 类型公里让 removeUnit (x:float<_>) =浮动 x让 foo = removeUnit 2.6 m让 foo2 = removeUnit 2.1<km>

<块引用>

val removeUnit : float<'u> -> float

I've got some data manipulation code which spits out csv at the end.

I started upgrading it to add units of measure everywhere, but I now have a problem with my csv function:

val WriteCSV : string -> 'a list array -> 'b list -> string -> unit

(the parameters are fileName, column array, column headers, separator)

Where I previously sent [|s;x;y|] to WriteCSV, I now have a problem, because I can't send [|skm; xmm; ymm|].

I tried writing a function for generically removing units of measure, but it doesn't work.

let removeUnit (n:float<_>) = n/1.0<_>

My questions are:

• Why doesn't it work?
• Can it be made to work?
• Is there another way to solve this particular problem?

解决方案

If I got your Problem right, casting it to "pure" float removes the Unit. For Example:

[<Measure>] type m
[<Measure>] type km

let removeUnit (x:float<_>) =
    float x

let foo = removeUnit 2.6<m>
let foo2 = removeUnit 2.1<km>

val removeUnit : float<'u> -> float

这篇关于如何一般地删除 F# 度量单位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！