[CDSlice]

Although it won't be as concise, you can use guards to emulate this feature with

    match data:
        case [x1, x2] if x1 == x2:
            ...

I agree on this being a fantastic addition to the language. I've sorely missed not having pattern matching in Python after using Rust.

[spott]

I think this is a better version. It is less ambiguous and more general. The [x,x] version isn't clear if it is using `__eq__` or `is`.

[RhysU]

Guards feel superfluous if the x, x pattern can be trivially lowered into a guard.

[repsilat]

More vice versa. Guards look more general (being able to express not-equal, and less-than etc), so special semantics for `x,x` only seem warranted if it's very common.

[RhysU]

Agreed they're more general. If I have a working guard implementation I can build the x, x case atop it. Meaning, the x, x case can be sugar.