Language Design: (More) Mistakes of Rust

(A random grabbag of things that I haven’t managed to include into the main article yet.)

• Strings don’t offer indexing, because it doesn’t make sense for UTF-8. Correct! But Strings offer slicing … WAT?

• Inconsistent naming. str and String, Path and PathBuf etc.

• Closures could be made to look much closer to functions, but somehow aren’t.

• “associated” functions in trait impls. I’d prefer separating them from normal functions and drop the self where possible.

• Arbitrary abbreviations all over the place. It’s 2017, your computer won’t run out of memory just because your compiler’s symbol table stores Buffer instead of Buf.

• Can someone decide on a casing rule for types, please, instead of mixing lowercase and uppercase names? Some types being “primitive” is an incredibly poor excuse.

• Also, having both CamelCase and methods_with_underscores?

• Single-use packages like std::option::Option, std::result::Result, std::default::Default.

• iter(), iter_mut(), into_iter() … decide prefix or postfix style and stick with it.

• Forward and backward annotations: #[foo] struct Foo {} vs struct Foo { #![foo] }.

• Type bounds are Sized by default, with some weird special syntax to opt out (?Sized).

• /// for normal documentation, //! for module level documentation. Documentation already uses Markdown, so maybe just let people drop a markdown file in the module dir? That would make documentation much more accessible when browsing through GitHub repositories.

• Also, documentation can cause compiler errors … that’s especially fun if you just commented a piece of code for testing/prototyping.

• Type alias misuse: In e.g. io crate: type Result<T> = Result<T, io::Error> … just call it IoResult.

• Compared to languages where macro invocation do not require special syntax (the !), the “obviousness” of invoking macros seems to have encouraged Rust developers to go completely over board in terms of magic.