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Comment by jimmaswell

7 years ago

I wish Rust would have kept saner OOP style classes from C++ instead of this bizarre trait stuff. The whole language feels like everything is just different for the sake of being different. Why is it "fn blah (x -> int.. -> int" or whatever when the rest of the tokens seem designed to save keystrokes at the cost of readability? Everyone is used to "int x(int y..". I've learned it some and the concepts around memory ownership and everything are good but the syntax is needlessly weird and annoying.

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jimmaswell

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blt  7 years ago

Special keywords like `fn` make parsing simpler. Trailing return types are useful in languages that support generic programming, because they make it easier to write a function whose return type depends on the types of its generic inputs. Even C++ has this feature now, using decltype and arrow notation:

    template<typename T, typename U>
    auto add(T t, U u) -> decltype(t + u)
    {
        return t + u;
    }

C++ is notoriously hard to parse. Consider the "most vexing parse", or the fact that refactoring tools for C++ are always flakier than their Java / C# / Go equivalents, or the fact that https://cdecl.org/ exists. New languages in the "expressive, high performance" niche cannot continue to be held back by C++ syntax.

  • jimmaswell  7 years ago

    C# and Java as you mentioned use very C++-like syntax.

    • joshuamorton  7 years ago

      To a first approximation, yes. But consider that the C++ grammar has ~100 more rules than Java (~170 vs. ~280), and parts of the C++ grammar are strongly context-dependent, which isn't true in Java.

feanaro  7 years ago

I actually greatly appreciate that function definitions begin with a dedicated keyword in Rust. I've always found it rather painful that definitions don't stand out from function calls in C and C++.

Retra  7 years ago

Rust is not based on C++. People coming from Haskell/ML aren't used to C's backwards type declarations, and that's why they're not in Rust; the people who make Rust have experience with more than just C/C++. So it's not different for the sake of being different, it is actually trying to be similar ... just not similar to C.

  • jimmaswell  7 years ago

    Similar to languages much fewer people use, instead of languages more commonly used as systems languages which Rust is meant to be.

    • steveklabnik  7 years ago

      In general, it’s a thing more newer languages are moving to, because it’s regarded as superior for a few different reasons. Mostly, it keeps the syntax more regular when you have type inference. See Kotlin as another recent example.

      In rust, we have additional reasons, and that’s because it’s not

        let name: type = expression;

      It’s

        let pattern: type = expression;

      Patterns offer more power than simple variable declarations. The names may not correspond 1-1 with the type, because you can create multiple names by destructuring more complex types

ChrisSD  7 years ago

C++ classes vs. Rust traits isn't just a matter of syntax differences.

Btw the function syntax is:

    fn foo(x: u16, y: u16) -> u32

If it were more C++ like it'd be:

    u32 foo(u16 x, u16 y)

Which is less keystrokes if anything.

  • kibwen  7 years ago

    Amusingly, C++ also supports Rust-style function headers, and has since C++11 (which is well before Rust was ever on the radar; really both C++ and Rust were inspired by ML here). The following two are identical in C++:

        u32 foo(u16 x, u16 y)
    auto foo(u16 x, u16 y) -> u32

    IIRC there are contexts where the former does not work and the latter is required, which I believe means that ML-style function headers are strictly more powerful in C++ than the original C-style function headers.

  • jimmaswell  7 years ago

    Exactly, they do stuff like fn yet make it longer than necessary otherwise.

    • the_why_of_y  7 years ago

      It depends... if your return type is nested inside a class and you're defining a member function, you'll have to write down a qualified return type name before the qualified member function name, whereas if the return type follows the function name, it can be unqualified because at that point the class extends the scope used for name lookup.

      http://www.stroustrup.com/C++11FAQ.html#suffix-return

    • vedantroy  7 years ago

      I am not a rust expert, but I assume the recent many programming languages have a keyword for function declaration is so that functions can be first class objects.

    • hellofunk  7 years ago

      This is one of the most trivial points I've ever heard for liking or disliking a programming language.

nullwasamistake  7 years ago

I agree. The language design is great, but they purposely use weird conventions everywhere. And by weird, I mean foreign to C++ programmers which is 90% of their user base.

They should have done what java did. Copy C++ syntax, only change it when needed. I've ported over java code where 2/3 of lines are nearly identical.

The async debacle is a great example of this. They settled on weird syntax instead of doing what every other language does, because of some holier than thou acedemic snobbery. If every other language does it that way, it would have worked fine in rust.

  • 0815test  7 years ago

    The Rust type syntax is not weird. C-like languages are weird, because their syntax grew by accretion from a much simpler use case where something like "int x;" or even "int f(int a, int b);" could make sense. But even typedefs famously screw that up, never mind everything else.

    > because of some holier than thou acedemic snobbery

    The async syntax was one of the most widely discussed issues in Rust development, and ergonomics concerns were key in what eventually was chosen. It's very misleading to describe it as your comment does.

    Re: parent comment, the Rust programming language book (free online) has a very nice section describing OOP-like patterns in Rust - as it turns out, the "good parts" of OOP are very nicely supported, and in a far simpler, more orthogonal way than what you get in C++. This means fewer dark corners in the language and something far easier to work with overall. Just because it may be different from what we did back in the 1990s, doesn't make it wrong!

    • nullwasamistake  7 years ago

      I really like rust, the design is great. I'm glad they cleaned up OOP and ditched nasty C++ stuff like templates.

      However, I went through the book recently and I'm quite annoyed that much of the syntax differs needlessly from C like languages. It massively increases the cognitive overhead for someone coming from Java, C++, C#, C-like language world.

      Rust is a systems language, it doesn't even have a runtime. 90%+ system level work is done in C-like languages. Rust syntax differs in countless pointless ways. I'm not saying it's wrong, it's just different in ways that don't matter from all other popular systems languages. Which is dumb.

      Things like "fn" instead of "function" and async syntax make Rust difficult to adopt by the target user base. Why fn? Is saving 6 characters worth confusing everyone?

      1 reply →

  • steveklabnik  7 years ago

    (It’s debatable that 90% of our user base is C++ programmers; in 2016, the last time we collected this data, it was 40%, and there’s no reason to believe it’s shifted THAT much since then.)

  • the_why_of_y  7 years ago

    One aspect of this that you might be overlooking is that the syntax for function pointers has to follow the syntax of function declarations.

    Why should a new language inflict this horror on its users:

    let i32 (*foobar)(i32, i32) = add;

    When it can do this instead:

    let foobar: fn(i32, i32) -> i32 = add;