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The Ultimate Guide to Rust Programming

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Using the format macro, I can write a function that turns an i32 into a String:

Rust 1.40.0
fn stringy(x: i32) -> String {
    format!("{}", x)
}
fn main() {
    assert_eq!(stringy(42), "42".to_owned());
    println!("Success!");
}

But we’re all about type parameters these days. Can we generalize this to any type T?

Rust 1.40.0
fn stringy<T>(x: T) -> String {
    format!("{}", x)
}

Not like that apparently:

error[E0277]: `T` doesn't implement `std::fmt::Display`
 --> src/main.rs:2:19
  |
2 |     format!("{}", x)
  |                   ^ `T` cannot be formatted with the default formatter
...