That sort of extreme flexibility simply does not exist. I mean it does but then you are firmly in the dynamic languages territory and you are forgoing any hope for close-to-the-metal performance.
fn setData(comptime pins: anytype, bus: anytype, data: u8) @TypeOf(bus)
That's why I claimed that no such language exists.
Rust is quite the opposite, more primitives that carry semantics (most of those in the stdlib though), a stronger but also more rigid type system, but those are pretty much needed for the compiler to guarantee safety.
The million dollar question is of course, can there be a more relaxed Rust with the same safety and performance guarantees, maybe by "squeezing the type inference engine" even more (and letting Rust look or somehow extract information across crate boundaries)? And do Rust programmers even see this as desirable, or are they mostly comfortable in their current sweet spot of the triangle?
Rust absolutely is not the end state of programming languages but I feel in many ways it's quite ahead than most of everything else. But yes, we still need something a tad better than it.
in rust, the P and B are resolved at compile time, not at runtime. If you wanted dynamic dispatch the types would be Box<dyn B>