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Comment by skrtskrt | Hacker News Reader

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skrtskrt

> Result<(), ()> is just a spicy bool.

EDIT: quoted wrong part of parent, ignore above

> match x { true => {} false => {} }

I really like this. Pattern matching syntax is great, nice to use in place of if/else as much as possible

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I disagree. There's a clippy lint against pattern matching on bool. I also think Result has the connotation of "success or error". Plus it's always annoying when a function returns an error that doesn't implement Error and I have to wrap/replace it to make it integrate with the standard error handling ecosystem.

There's a nice alternative though, which is empty struct errors.

    #[derive(Debug, thiserror::Error, displays of::Display)]
    /// Frobnicating the foo failed.
    struct FrobError;

The advantage is the standard advantages types use, i.e. if I want to propagate it I know this specific zero sized type has a specific meaning. It'll also show a nice message if you print it.

I like matching on bools on the same cases where someone wouldn't write braces around the body in C: whenever the corresponding expressions keep you under the line length. For example:

    let plural = match cases.len() > 1 {
        true => "s",
        false => "",
    };

Of course, you'd more likely have something like

    let prefix = match cases.len() {
        0 => "no values".to_string(),
        1 => "a value".to_string(),
        n => format!("{} values", n),
    };

Interesting. I prefer writing that as an if/else on one line when rufmt lets me, but I see your point.

    let plural = match cases.len() {
        1.. => "s",
        0 => "",
    };

That's not the correct plural rule in English, you'd want

    let plural = match cases.len() {
        0 | 2.. => "s",
        1 => "",
    };

or something (though to be fair the original code snippet also handled "0" incorrectly -- should be "cases.len() != 1").

And also to be fair you probably don't want to be hardcoding English pluralization rules.

I used to maintain a library which actually tried to implement proper English pluralization rules. I can confirm you don't want to do that.

My favorite thing about internationalization is that some languages have 6 different translations for different amounts.

Hang on aren't we conflating two things in this thread? Or you quoted the wrong half of GP's comment perhaps? You can pattern match on an actual `bool`; if you use `Result<(), ()>` instead you'll have to match on `Ok(_)`/`Err(_)`, which is bad because one of your Boolean values is an 'error' now, and also because which one is is up to you (to remember)!

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