To be fair, you can bind to any name. So, binding to `a` instead of `_` would work as well. You could then use that bound value in the corresponding expression.

To be fair, you can bind to any name. So, binding to `a` instead of `_` would work as well. You could then use that bound value in the corresponding expression. However, I would have expected rustc to complain about unused variables in fn main() { for i in range(1i, 101) { match (i % 3, i % 5) { (0, 0) => println!("Fizzbuzz"), (0, a) => println!("Fizz"), (b, 0) => println!("Buzz"), c => println!("{}", i), } } } but neither the playpen nor yesterdays snapshot complains. And if you want to suppress warnings about unused variables, you prefix the variable with an underscore, or just use only the underscore, which got common to mean "I don't care what value gets bound to this name.". fn main() { let a = 0u; } compiles with warning: unused variable: `a`, but fn main() { let _a = 0u; } compiles silently.