ParseInteger and ParseBoolean

[sindresorhus]

Would it be useful to be able to convert a number in a string to a number literal type? '100' => 100.

I guess a more strictly typed Number.parseInt could take advantage of this.

type SomeNum = "100" extends `${infer U extends number}` ? U : never;
// 100

• https://devblogs.microsoft.com/typescript/announcing-typescript-4-8/#improved-inference-for-infer-types-in-template-string-types
• More specific inference for constrained 'infer' types in template literal types microsoft/TypeScript#48094

We cannot do ParseNumber because if it doesn't match exactly, it just returns a number type instead of 100:

type SomeNum = "100.0" extends `${infer U extends number}` ? U : never;
// number

We could also maybe do ParseBoolean and maybe Is methods too (IsInteger)?

Maybe it's not that useful. Feedback wanted.

[anuraghazra]

Hey landed here while I was exploring the 48094 PR.
I think a type level string to number would be handy in some situations.

We cannot do ParseNumber because if it doesn't match exactly, it just returns a number type instead of 100:

Yes, that's a bummer. But actually I found a workaround.

https://tsplay.dev/mbn8Pm

Here's the tweet where I was geeking about this today