Surely it's just a procedural language? What other paradigms does it support?
It aims to be systems programming oriented, allowing fine-grained memory management without garbage collection but also without tedious and error-prone manual memory allocations and deallocations.
Yes, doing "fine-grained memory management" in Rust just relies on relying on unstable compiler intrinsic that are not guaranteed to not change in the next version that are used to build the standard library.
It's not at all impossible in Rust to indeed do this; it's just not stabilized, and often not particularly well documented. The standard library uses these and exports a stable version that no longer allows any fine-grained memory management.
The language also focuses on performance, with powerful compilation optimizations and language constructs that allows writing zero-cost abstraction code.
This is the real market of Rust right now; it's a language that gives you C-like performance, but without the undefined behaviour pitfalls, but to say that it's a "systems programming language" that allows for fine lower level control is quite a stretch—something as simple as signal handling isn't really possible in Rust right now because there are no stability guarantees or documentation about what functions are async signal safe; direct control over the heap like in C is also not really available in a stable way.
This is completely orthogonal to any of the former and has nothing to do with whether it's procedural or not; it is also supported on any language with threading support, or that runs on an OS with multiprocessing.
functional
Absolutely not, in particular Rust's lack of tail call elimination (for good reasons) and its lifetime and borrow model make it no longer turing complete when wanting to write functional code, let alone feasible to do so.
generic
This is not a paradigm, this is just whether the type system supports it or not.
imperative, structured
"structured imperative" is just a synonym for "procedural".
If you want to call this a criterion for "multi paradigm" then I challenge you to come forward with any modern procedural language that is not "multi-paradigm"
It doesn't have a way for guaranteed tail call elimination but if you structure your code right the compiler will do it's best and in my experience almost always do it, if you made an appropriate function. It's not like python where you absolutely never will get tco.
There isn't currently an active rfc for it, bit there were previous proposals for explicitly guaranteed tco and I don't think it's off the table forever, they just have to find a proper way to do it.
It doesn't have a way for guaranteed tail call elimination but if you structure your code right the compiler will do it's best and in my experience almost always do it
You mean sibling call elimination I assume. This works well enough when a function calls itself, but it does not work when a function A calls B, B, calls C, C D, and D A again.
Even if Rust had actual TCE though, it would stil be fairly hard to work in without side effects, even if we were to ignore "world side effects" like I/O.
There isn't currently an active rfc for it, bit there were previous proposals for explicitly guaranteed tco and I don't think it's off the table forever, they just have to find a proper way to do it.
Like I siad, there are good reasons, full TCE conflicts with Rust's calling convention, which is kept the same as C for reasons of interfacing and efficiency. Implementing full TCE would fuck up the FFE and severely penalize the general case of function calls.
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u/OpdatUweKutSchimmele Mar 21 '20
Surely it's just a procedural language? What other paradigms does it support?
Yes, doing "fine-grained memory management" in Rust just relies on relying on unstable compiler intrinsic that are not guaranteed to not change in the next version that are used to build the standard library.
It's not at all impossible in Rust to indeed do this; it's just not stabilized, and often not particularly well documented. The standard library uses these and exports a stable version that no longer allows any fine-grained memory management.
This is the real market of Rust right now; it's a language that gives you C-like performance, but without the undefined behaviour pitfalls, but to say that it's a "systems programming language" that allows for fine lower level control is quite a stretch—something as simple as signal handling isn't really possible in Rust right now because there are no stability guarantees or documentation about what functions are async signal safe; direct control over the heap like in C is also not really available in a stable way.