Comment by lightgreen | Hacker News Reader

Comment by lightgreen | Hacker News Reader

Parent Full thread

> A really clean approach to handling Maybe results that

Rust has exactly the same question mark syntax, and obviously V copied it from Rust.

Copying good ideas from other languages is right.

> I haven't seen in other languages before

But you did not know that the syntax was derived from Rust. And the value of a review of some programming language from a person without basic knowledge of the space is not very helpful.

It's likely that you missed a lot of other important details. Like this one:

> V is essentially a much cleaner version of Go, syntactically

Syntactically only, yes. But it is very different from Go, because it does not do garbage collection.

Sorry.

V's Maybes are different than Rust's, only the ? syntax is similar

1. Option/Result are unified into a single type, ?T.

2. It is not parameterized over the error type.

3. The Ok() case does not need to be marked (ex. you write 1, not Ok(1)).

4. In addition to the x? sugar, there is also x or { ... } sugar, which is like Rust's x.unwrap_or(|err| ...) except without the closure so you can eg. break or return from the block. There is also if y := x { .. } else { ... }, which is like Rust's match x { Ok(y) => ..., Err(err) => ... }.

These are all reasons you could think V has cleaner Maybe handling than other languages.

> 1. Option/Result are unified into a single type, ?T.

This is not a positive. Option<T> and Result<T, E> have semantically different meanings. This is like saying integers and strings have been unified into a single type: string.

Ah, I meant the "or" operator, in Rust you have to match on the option result right?

  match maybe_error {
    Ok/Some(val) =>
    None/Err =>
  }

You can do

result.or_else(|err| ... )

Or

result.map(|value| ... )

Ah welp, fair enough that's on me for being clueless. Edited my answer.

You can do result or { break }. You can't do that from a closure.

Reply on news.ycombinator.com