Rust Tuple Structs Give Positional Data a Distinct Type

A tuple struct has a name and positional fields. Each tuple struct definition creates its own type, even when another tuple struct contains the same field types in source

struct Meters(u32);
struct Seconds(u32);
 
fn print_distance(distance: Meters) {
    println!("{} meters", distance.0);
}
 
fn main() {
    let distance = Meters(100);
    let time = Seconds(20);
 
    print_distance(distance);
    println!("{} seconds", time.0);
}

We access a tuple struct field by position, so distance.0 is its first field. Meters(100) and Seconds(20) both contain a u32, but Meters and Seconds are different types. Replace print_distance(distance) with print_distance(time) and run cargo check to see the mismatch.

A named-field struct helps when the individual fields need descriptive names. A tuple struct helps when the type name carries the meaning and the fields’ positions are clear.