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Rust has no explicit goal to introduce magic - instead the goal is to be safe and sound. I'd argue the code very often compiles to what one might expect it to c

Rust has no explicit goal to introduce magic - instead the goal is to be safe and sound. I'd argue the code very often compiles to what one might expect it to compile to, its certainly better than C++ when it comes to magic in terms of how useful and transparent said magic is.

j-pb 4y ago
C++ is arguably the most complex programming language ever. There is not much to be gained by comparing against the supremum. Take a look at the languages that rust was influenced by (https://en.wikipedia.org/wiki/Rust_(programming_language) https://en.wikipedia.org/wiki/Rust_(programming_language)) those aren't languages with straightforward compilation semantics. There is a reason why rust has a datalog engine build into the compiler (https://github.com/rust-lang/datafrog https://github.com/rust-lang/datafrog). Which is imho totally rad and awesome, but really hard to fully form a mental model of without a spec.
- Rusky 4y ago
  This is pretty vague reasoning. Rust draws inspiration from each of those languages for something but that doesn't mean they affect its operational semantics, which are quite similar to C's. The fact that you point to datafrog is illustrative: while it is not actually built into the compiler today, the use case for it is borrow checking, which famously does not impact the language's operational behavior at all! It is purely a compile-time analysis that does not influence code generation. (For example, consider that mrustc and the GCC frontend are both able to omit borrow checking entirely and yet still produce runnable binaries!) Of course, the borrow checker is still something that you need to build a mental model for, but by design it is okay for you to get that wrong occasionally, because the result can only ever be "your program still does what you thought, but the analysis proved that in a way you did not expect" or "your program does not compile."
- pjmlp 4y ago
  I bet PL/I, Ada, and even Python 3 aren't far off. Same applies to the Java and .NET ecosystem, because either you swim on the surface, or you really get to know how the implementations, down to bytecode, JIT, GC and standard libraries work, and now they are full speed ahead with 6 month release schedules.
cztomsik 4y ago
after 5ys of (hobby but frequent) rust I'm pretty confident most people cannot tell what their code will compile to and what its runtime profile is going to be (aka you can't reason about performance -> so there is a lot of magic/complexity) I've recently tried Zig and switched to it instantly, it's hard to explain but basically Andrew has a very good taste at picking important features and keeping the language complexity very low. You know how it takes some time to learn borrow checker and macros and generics and traits and all weird rules of what you cannot do and then trait bounds and then it doesn't work exactly like you need, or the crate does not support something and you cannot implement it yourself, etc. etc. So in Zig I had a hello world on day one, and the first thing I did was encode/decode ANY json messages for tagged union (which unfortunately is not supported in std but it was very easy to do it myself) and it worked! I did this the first day in entirely new language (I was not even doing C/C++ before) and it would probably take few days in rust and I'd probably mess up something and I know it wouldn't work for every case and every crate, because of orphan rule. In Zig it would work for any struct, internal or external. And also Debug, Display, Eq, Partial, all of that works automatically. That's huge! And the worst thing is that recently, I've started using pointers again, and when I look at the code I don't see anything unsafe in the structure itself, it can be used unsafely but that is also very easy to fix in Zig because you have these explicit allocator and it's so easy to put everything in the same arena transparently, or use SegmentedList with stable pointers.

j-pb 4y ago

C++ is arguably the most complex programming language ever. There is not much to be gained by comparing against the supremum. Take a look at the languages that rust was influenced by (https://en.wikipedia.org/wiki/Rust_(programming_language) https://en.wikipedia.org/wiki/Rust_(programming_language)) those aren't languages with straightforward compilation semantics. There is a reason why rust has a datalog engine build into the compiler (https://github.com/rust-lang/datafrog https://github.com/rust-lang/datafrog). Which is imho totally rad and awesome, but really hard to fully form a mental model of without a spec.

Rusky 4y ago
This is pretty vague reasoning. Rust draws inspiration from each of those languages for something but that doesn't mean they affect its operational semantics, which are quite similar to C's. The fact that you point to datafrog is illustrative: while it is not actually built into the compiler today, the use case for it is borrow checking, which famously does not impact the language's operational behavior at all! It is purely a compile-time analysis that does not influence code generation. (For example, consider that mrustc and the GCC frontend are both able to omit borrow checking entirely and yet still produce runnable binaries!) Of course, the borrow checker is still something that you need to build a mental model for, but by design it is okay for you to get that wrong occasionally, because the result can only ever be "your program still does what you thought, but the analysis proved that in a way you did not expect" or "your program does not compile."
pjmlp 4y ago
I bet PL/I, Ada, and even Python 3 aren't far off. Same applies to the Java and .NET ecosystem, because either you swim on the surface, or you really get to know how the implementations, down to bytecode, JIT, GC and standard libraries work, and now they are full speed ahead with 6 month release schedules.

cztomsik 4y ago

after 5ys of (hobby but frequent) rust I'm pretty confident most people cannot tell what their code will compile to and what its runtime profile is going to be (aka you can't reason about performance -> so there is a lot of magic/complexity) I've recently tried Zig and switched to it instantly, it's hard to explain but basically Andrew has a very good taste at picking important features and keeping the language complexity very low. You know how it takes some time to learn borrow checker and macros and generics and traits and all weird rules of what you cannot do and then trait bounds and then it doesn't work exactly like you need, or the crate does not support something and you cannot implement it yourself, etc. etc. So in Zig I had a hello world on day one, and the first thing I did was encode/decode ANY json messages for tagged union (which unfortunately is not supported in std but it was very easy to do it myself) and it worked! I did this the first day in entirely new language (I was not even doing C/C++ before) and it would probably take few days in rust and I'd probably mess up something and I know it wouldn't work for every case and every crate, because of orphan rule. In Zig it would work for any struct, internal or external. And also Debug, Display, Eq, Partial, all of that works automatically. That's huge! And the worst thing is that recently, I've started using pointers again, and when I look at the code I don't see anything unsafe in the structure itself, it can be used unsafely but that is also very easy to fix in Zig because you have these explicit allocator and it's so easy to put everything in the same arena transparently, or use SegmentedList with stable pointers.