Update 'let is used to introduce variables' paragraph

[bombless]

I think "let is used to introduce variables" is incorrent.
You can use

match (42, true) {
    (x, y) => { /* ... */ }
}

to replace

let x = 42;
let y = true;

so it's nothing special for let.

[rust-highfive]

r? @pcwalton

(rust_highfive has picked a reviewer for you, use r? to override)

[bombless]

Thanks for @jorisgio reminding me that the binding of let can happen later in control flow.
So it is one reason to remain the doc as-is.

But consider this:

fn main() {
    let (x, (y,));
    x = 10;
    y = true;
}

playpen
If you say this let is introducing variables, I don't want to believe that.

I still suggest there's no "variable definition" in Rust.

[jorisgio]

In my opinion, in let mut x = 4; x += 1;, x is a variable. As for the let x; it's just a split binding pattern.

[steveklabnik]

there should be a newline after this, to make a new paragraph. also, the wrapping seems a bit odd.

[steveklabnik]

The official term is 'variable bindings', though sometimes, people just say one or the other.

[steveklabnik]

I would prefer to change this to "Why is let used to introduce variables?"

[steveklabnik]

I do think this needs improvement and this is overall an improvement, just some nits :)

[bombless]

Thanks :)
r? @steveklabnik

[steveklabnik]

@bors: r+ rollup

[bors]

📌 Commit c9454b1 has been approved by steveklabnik

[bombless]

I missed a case here: for-in also do pattern matching.
I'll try update it.