Possible typo in Chapter 19.2: missing if in if let examples

[raymalt]

Hi Rust Book team,

Thank you for your amazing work on the Rust Book, it’s been an incredibly helpful resource for learning Rust!

While reading Chapter 19.2 on Refutability, I noticed that a couple of examples seem to be missing the if keyword in what appear to be if let statements.

For example, there’s an instance like this:

let Some(x) = a_value {
// …
}

I believe this might be a typo, and it should instead be:

if let Some(x) = a_value {
// …
}

As far as I understand, using let like that without if would result in a compilation error due to the pattern possibly being non-exhaustive.

Of course, please correct me if I’ve misunderstood the context. Just wanted to point this out in case it’s unintentional.

Thanks!

[iampi31415]

let like that without if would result in a compilation error (...)

Yes. Although there is let...else as well.

please correct me if I’ve misunderstood the context.

If you refer to listing 19-8 then you've misunderstood the context.

It is showing that it doesn't compile because refutable patterns need the else clause or using if let like you indicated. Also, the crab has the ? which implies that running it errors.

---

There is a related issue though, that may be what confused you. The text before and after listing 19-9 says:

we can use if let

but uses let...else (and says so in the caption as well). So if you were expecting to see an if then it may be puzzling.

The text should say "we can use let...else". Or the examples should use if and then all the rest needs to be updated (more effort)

So currently they are out-of-sync.