Creating a unique set of types in tuple

help
1

Hi,
i'm trying to create a unique set of types for example of a Tuple:
e.g.
(usize,usize,usize)-> usize
(usize,u64,usize)-> (usize,u64)
As a starting point a i tried:

pub trait UniqueType {
    type ReducedType;
}

impl<A, B> UniqueType for (A, B)
{
    type ReducedType = Self;
}
impl<A> UniqueType for (A, A)
{
    type ReducedType = A;
}

which doesn't compile due to overlap.
for guarding the different implementations i tried all kinds of unstable features like const expr by making the trait generic over a bool and checking for identical type ids, auto traits with negative impl - they don't work for generic types, specialisation(doesn't work well with associated types) a.s.o but even with these features i couldn't produce a working version even for the must simple case above.
Any hint would be highly appreciated.

2

What you're asking for is a kind of specialization, because anything that does “if these two types are not equal, then ...” is a kind of specialization. I can't tell you how to do it because I don't write code using the specialization feature, but you definitely can't achieve it without specialization.

3

This feels like an XY problem. What is the actual engineering problem you are trying to solve that led you down this path? Perhaps there is a better way to do that thing.

4

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