Nick! Comments - Answer Overflow

But the "actual" reason that Mojo doesn't use &' syntax is that in Rust, &T is a built-in type, whereas in Mojo, the equivalent type is Pointer which is not a built-in type. It's just a struct, so it's given a regular name, like other structs.

23 replies

MModular

•Created by jmky on 10/7/2024 in #questions

Is there a disdain for Rust from the Mojo team?

@jmky Mojo's "lifetimes" don't actually work the same as Rust. They behave very, very differently. Given this, there's no real reason to make them visually similar. If anything, that would lead to more confusion, not less, because Rust programmers would expect Mojo references to behave the same as Rust references, which they don't, by design.

23 replies

MModular

•Created by Carbon on 10/5/2024 in #questions

Mojo vs Rust memory safety

To address just one point: I expect Mojo will offer some form of access control eventually. It would be easy to do and has many benefits beyond safety, e.g. API versioning. But more generally, I understand what you're saying. I guess time will tell how the ethos of Mojo vs. Rust ends up differing.

16 replies

MModular

•Created by Carbon on 10/5/2024 in #questions

Mojo vs Rust memory safety

I'm not sure I agree with that characterization. 🫢 Mojo and Rust both have safe references, and unsafe references. But yes, perhaps Mojo programmers will choose to use unsafe operations more often, for the sake of optimization.

16 replies

MModular

•Created by Carbon on 10/5/2024 in #questions

Value Semantics and async code

I'd say the jury is still out on function color. If we can find a good way to avoid color, we will. But as of today, there is no agreement that it can be avoided.

6 replies

MModular

•Created by banananas on 9/23/2024 in #questions

"Linking" structs together?

(Also I think Variant should be renamed to Tagged, since it's meant to be a tagged union.)

44 replies

MModular

•Created by banananas on 9/23/2024 in #questions

"Linking" structs together?

Basically you can always replace a sum type declaration with an alias, e.g. alias Error = Variant[Error1, Error2, Error3]. But we need to upgrade the UX of Variant so that it matches sum types.

44 replies

MModular

•Created by banananas on 9/23/2024 in #questions

"Linking" structs together?

I'm talking about a hypothetical future version of Variant. I haven't completed a design for that.

44 replies

MModular

•Created by banananas on 9/23/2024 in #questions

"Linking" structs together?

(Mojo doesn't need enums for that to be nicer. It just needs a refined version of Variant, plus support for the sugar MyStruct|MyOtherStruct.)

44 replies

MModular

•Created by AM on 4/22/2024 in #questions

effects system?

I/O can be modelled as reading and/or mutating a data source, so IMO it falls into the “tracking mutation” bucket.

4 replies

MModular

•Created by AM on 4/22/2024 in #questions

effects system?

Different people mean different things when they say “effect system”. In your mind, what does an effect system do, and how would it improve Mojo? Mojo already tracks exceptions in function signatures. It also tracks some kinds of mutation (argument mutation), and it will track additional kinds of mutation once references are finalized.

4 replies

MModular

•Created by Grandimam on 4/12/2024 in #questions

Transfer operator inside constructor and moveinit

@Grandimam Actually, that's not the full story. When the ^ sigil is used in expressions of the form y = x^, it triggers the invocation of the move constructor (__moveinit__) on x. (So in the program you posted, the move constructor that is being defined calls another move constructor.) In other words, the ^ operator has two distinct purposes: - To signal that the lifetime of a variable will end. - To invoke __moveinit__, when it is used in expressions of the form y = x^.

11 replies

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