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Comment by masklinn | Hacker News Reader

> What am I looking at there? Are those all traits on Vec that I then have to parse mentally so I can understand what I can do with it? Are all those pages basically to say "Vec works like an array of T"?

No. The type which tells you that Vec works like a slice of T is https://doc.rust-lang.org/std/vec/struct.Vec.html#impl-Deref

The others are separate abstract operations which are available (implemented) on vecs e.g. AsRef/AsMut denote that you can trivially get a (mutable) reference to the parameter from a vec. The implementations are similarly trivial (https://doc.rust-lang.org/src/alloc/vec.rs.html#2348-2374).

> I'm sure some people find this documentation helpful, but it doesn't look as useful to me as map's simple one-liner.

Do you mean this one?

    auto auto map(Range) (Range r)

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I’ve not looked much into D, but I’ve really been enjoying Rust.

I think the main takeaway is that there are very different ways of approaching language design. In Rust there was a decision to make the function signature the single place which defines the guaranteed input and output types to a function, but that is a trade-off. It encourages a more complex type system, as the flexibility of functions is on a sense constrained by the type system. Personally I like that explicitness, since there is only one place to look. In the future features like const generics and GATs will make that more powerful.

But on the other hand, D appears to be able to support much more complex types (possibly dependent types?) by not requiring that the type system can express them directly. In a sense the whole language can be used to define types. That’s a cool thing to be able to do, even if it means having to inspect documentation and method bodies to work out what they do.

On the "auto auto", I'm pretty sure I filed a bug report on that. There are alternate D docs that don't produce the "auto auto" (and it goes without saying that it isn't that way in the code itself).

No this one:

"Returns: A range with each fun applied to all the elements. If there is more than one fun, the element type will be Tuple containing one element for each fun."

To get that degree of flexibility in Rust you’d have to turn to macros, then the return type will depend on the generated code. That could be pretty much anything, so you’d need to read the docs anyway. Perhaps the languages are not that different after all.

D’s syntax for the template body looks much more similar to normal D code, in Rust the pattern macro syntax is like a language to itself and procedural macros need a fair bit of boilerplate, including explicit “quote” blocks.

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