Making Rust's macros easier is laudable. Purely from a user's perspective I find it especially annoying, that proc macros need their own crate, even if I understand the reasons for it.
If I read Crabtime correctly it solves that problem, which is nice.
That being said Crabtime looks more like compile time eval on steroids to me than an analogon to Zig's comptime.
One (maybe the) distinguishing feature between comptime in Zig and Rust macros seems to me to be access to type information. In Zig you have it[1]
in Rust you don't and that makes a big difference. It doesn't look like we will get that in Rust anytime soon and the projects that need it (e.g. cargo semver check) use dirty tricks (parsing RustDoc from the macro) to accomplish it. I did not see anything like that in Crabtime, but I might have missed it. At any rate, I'd expect compile time reflection for anything that claims to bring comptime to Rust.
[1] I think, but I am not a Zig expert, so please correct me if I am wrong.
Making Rust's macros easier is laudable. Purely from a user's perspective I find it especially annoying, that proc macros need their own crate, even if I understand the reasons for it. If I read Crabtime correctly it solves that problem, which is nice.
That being said Crabtime looks more like compile time eval on steroids to me than an analogon to Zig's comptime.
One (maybe the) distinguishing feature between comptime in Zig and Rust macros seems to me to be access to type information. In Zig you have it[1] in Rust you don't and that makes a big difference. It doesn't look like we will get that in Rust anytime soon and the projects that need it (e.g. cargo semver check) use dirty tricks (parsing RustDoc from the macro) to accomplish it. I did not see anything like that in Crabtime, but I might have missed it. At any rate, I'd expect compile time reflection for anything that claims to bring comptime to Rust.
[1] I think, but I am not a Zig expert, so please correct me if I am wrong.