What needs to be explained about lifetime parameters

[mdinger]

Another question with some excellent analysis which asks what the <'a, 'b> in Foo<'a, 'b> means among other things:

There is a time in your life when you have to understand lifetimes

Hi, Sorry for the stupid title of this post I am afraid that I didn't clear understand how the lifetimes work, despite I have read Rust book and Rust by example, I still don't get them! For example take this simple case: fn foo<'a>(x: &'a T) -> &'a U { ... } I would read it as: foo is a function that takes an argument named x that is a reference to type T and returns a reference to a value of type U, x should have the same lifetime of the returned value Is that right? So what abou…