Do you mean rewrite And and Or with Xor? I feels it makes more sense to write Xor using And and Or, like:

type Xor<A extends boolean, B extends boolean> = Or<And<Not<A>, B>, And<A, Not<B>>>;

But this would currently not work because Not doesn't handle never properly. So, your implementation is fine, just remove this comment.

Ohh no, the comment point to IfNever that i want to use to simplify this pattern

type T = _Or<If<IsNever<A>, false, A>, If<IsNever<B>, false, B>>

which is used in Or and repeats multiple unnecessary checks trough the process and IfNever is a custom private types between Xor and Or which directly infer the result:

type T = _Or<IfNever<A>, IfNever<B>>

I was going to use And and Or for this, but the extra conditions didn’t make much sense to me — why prettify things and lose performance?

A working Xor would look like this:

type Xor<A extends boolean, B extends boolean> = And<Or<A, B>, Not<And<A, B>>>;

Ohh no, the comment point to IfNever that i want to use to simplify this pattern

No, please remove this abstraction and use <If<IsNever<T>, false, T>, similar to how it’s done in Or:

It's quite simple and easy to understand and doesn't need further abstraction.

I was going to use And and Or for this, but the extra conditions didn’t make much sense to me — why prettify things and lose performance?

There's NO performance loss as such, and it's actually better doing it with And and Or because it helps validate that And and Or themselves are implemented correctly. But, it's fine for now.

Okay, I'll use ur seggestion for IfNever.
For the And and Or version of Xor it does work perfectly, I test it. If it's better to make it this way tell me.

For the And and Or version of Xor it does work perfectly, I test it. If it's better to make it this way tell me.

Yeah, let's do it using And, Or & Not.

Either definition works:

1. A working Xor would look like this:

   type Xor<A extends boolean, B extends boolean> = And<Or<A, B>, Not<And<A, B>>>;

2. I feels it makes more sense to write Xor using And and Or, like:

   type Xor<A extends boolean, B extends boolean> = Or<And<Not<A>, B>, And<A, Not<B>>>;