将数字类型转换为对应的字符串一 [英] Convert number type to corresponding string one

问题描述

例如，我有一些带有具体数字的类型

I have some type with concrete number, for example

type Num = 42;

现在我要使转换成为通用

Now I want to make converting generic

type NumberToString<N> = ... // N as string instead of number

如此

type A = NumberToString<Num>; // "42"
type B = NumberToString<1>;   // "1"

我怎么写这样的转换器?

How can I write such converter?

推荐答案

我认为任意数字都不可行.有一个未解决的问题表面上致力于在类型系统中进行数学运算，但没什么大不了的据我所知发生在那里.

I don't think that's possible for arbitrary numbers. There's an open issue ostensibly dedicated to doing math in the type system, but nothing much is happening there as far as I can see.

如果您可以将其限制为在合理"范围内的非负整数，则可以在某处声明一个巨大的元组，并按如下所示进行操作:

If you're okay limiting it to non-negative whole numbers in a "reasonable" range, you can declare a huge tuple somewhere and do it like this:

type HugeTuple = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0]; // as long as you need
type NumToStr<N extends number> = { [K in keyof HugeTuple]: K }[N];

type One = NumToStr<1>; // "1"
type TwoOrFortyTwo = NumToStr<2 | 42> // "2" | "42"

所以，呃，你去了.祝你好运！

So, uh, there you go. Good luck!

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