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55 points anqurvanillapy | 1 comments | | HN request time: 0.298s | source

Hi I'm Anqur, a senior software engineer with different backgrounds where development in C was often an important part of my work. E.g.

1) Game: A Chinese/Vietnam game with C/C++ for making server/client, Lua for scripting [1]. 2) Embedded systems: Switch/router with network stack all written in C [2]. 3) (Networked) file system: Ceph FS client, which is a kernel module. [3]

(I left some unnecessary details in links, but are true projects I used to work on.)

Recently, there's a hot topic about Rust and C in kernel and a message [4] just draws my attention, where it talks about the "Rust" experiment in kernel development:

> I'd like to understand what the goal of this Rust "experiment" is: If we want to fix existing issues with memory safety we need to do that for existing code and find ways to retrofit it.

So for many years, I keep thinking about having a new C dialect for retrofitting the problems, but of C itself.

Sometimes big systems and software (e.g. OS, browsers, databases) could be made entirely in different languages like C++, Rust, D, Zig, etc. But typically, like I slightly mentioned above, making a good filesystem client requires one to write kernel modules (i.e. to provide a VFS implementation. I do know FUSE, but I believe it's better if one could use VFS directly), it's not always feasible to switch languages.

And I still love C, for its unique "bare-bone" experience:

1) Just talk to the platform, almost all the platforms speak C. Nothing like Rust's PAL (platform-agnostic layer) is needed. 2) Just talk to other languages, C is the lingua franca (except Go needs no libc by default). Not to mention if I want WebAssembly to talk to Rust, `extern "C"` is need in Rust code. 3) Just a libc, widely available, write my own data structures carefully. Since usually one is writing some critical components of a bigger system in C, it's just okay there are not many choices of existing libraries to use. 4) I don't need an over-generalized generics functionality, use of generics is quite limited.

So unlike a few `unsafe` in a safe Rust, I want something like a few "safe" in an ambient "unsafe" C dialect. But I'm not saying "unsafe" is good or bad, I'm saying that "don't talk about unsafe vs safe", it's C itself, you wouldn't say anything is "safe" or "unsafe" in C.

Actually I'm also an expert on implementing advanced type systems, some of my works include:

1) A row-polymorphic JavaScript dialect [5]. 2) A tiny theorem prover with Lean 4 syntax in less than 1K LOC [6]. 3) A Rust dialect with reuse analysis [7].

Language features like generics, compile-time eval, trait/typeclass, bidirectional typechecking are trivial for me, I successfully implemented them above.

For the retrofitted C, these features initially come to my mind:

1) Code generation directly to C, no LLVM IR, no machine code. 2) Module, like C++20 module, to eliminate use of headers. 3) Compile-time eval, type-level computation, like `malloc(int)` is actually a thing. 4) Tactics-like metaprogramming to generate definitions, acting like type-safe macros. 5) Quantitative types [8] to track the use of resources (pointers, FDs). The typechecker tells the user how to insert `free` in all possible positions, don't do anything like RAII. 6) Limited lifetime checking, but some people tells me lifetime is not needed in such a language.

Any further insights? Shall I kickstart such project? Please I need your ideas very much.

[1]: https://vi.wikipedia.org/wiki/V%C3%B5_L%C3%A2m_Truy%E1%BB%81...

[2]: https://e.huawei.com/en/products/optical-access/ma5800

[3]: https://docs.ceph.com/en/reef/cephfs/

[4]: https://lore.kernel.org/rust-for-linux/Z7SwcnUzjZYfuJ4-@infr...

[5]: https://github.com/rowscript/rowscript

[6]: https://github.com/anqurvanillapy/TinyLean

[7]: https://github.com/SchrodingerZhu/reussir-lang

[8]: https://bentnib.org/quantitative-type-theory.html

Show context
fxtentacle ◴[] No.43176363[source]
I believe what programmers actually want is clean dialect-free C with sidecar files.

It seems people pretty universally dislike type annotations and overly verbose comments, like Ruby's YARD or Java's Javadoc. Also, if your new language doesn't compile with a standard C compiler, kernel usage is probably DOA. That means you want to keep the source code pure C and store additional data in an additional file. That additional file would then contain stuff like pointer type annotations, object lifecycle and lifetime hints, compile-time eval hints, and stuff to make the macros type safe. Ideally, your tool can then use the C code and the sidecar file together to prove that the C code is bug-free and that pointers are handled correctly. That would make your language as safe as Rust to use.

The hardcore C kernel folks can then just look at the C code and be happy. And you and your users use a special IDE to modify the C code and the sidecar file simultaneously, which unlocks all the additional language features. But as soon as you hit save, the editor converts its internal representation back into plain C code. That means, technically, the sidecar file and your IDE are a fancy way of transpiling from whatever you come up with to pure C.

replies(1): >>43181933 #
1. anqurvanillapy ◴[] No.43181933[source]
I love this idea so much.

I got stuck at how to tackle "new language doesn't compile with a standard C compiler" for many times, but my solution is much worse than yours: Like LuaJIT, they left one unreadable "minilua" C file [1] to bootstrap some stuff, we could have a source-code version of the "new C" compiler, compile things twice. That sounds bad.

For languages with a very advanced type system that compiles to C, I could only think of Koka [2], which translates the "algebraic effect and handlers" code into pure C, achieving pure C generators, coroutines and async/await without the support of setjmp/setcontext. But the generated C code is unreadable, I would definitely think about how to handle the readability and debugging issue with sidecar files.

[1]: https://github.com/LuaJIT/LuaJIT/blob/v2.1/src/host/minilua....

[2]: https://koka-lang.github.io/koka/doc/book.html