From 15135550e05f1ae812fb69731791088ba4fbffb4 Mon Sep 17 00:00:00 2001 From: Noratrieb <48135649+Noratrieb@users.noreply.github.com> Date: Thu, 9 Oct 2025 22:25:42 +0200 Subject: [PATCH 1/3] gamingg --- .../posts/item-pattern-and-struct-await.md | 123 ++++++++++++++++++ 1 file changed, 123 insertions(+) create mode 100644 blog/content/posts/item-pattern-and-struct-await.md diff --git a/blog/content/posts/item-pattern-and-struct-await.md b/blog/content/posts/item-pattern-and-struct-await.md new file mode 100644 index 0000000..facf44f --- /dev/null +++ b/blog/content/posts/item-pattern-and-struct-await.md @@ -0,0 +1,123 @@ ++++ +title = "Item Patterns and Struct Await" +date = "2025-10-09" +author = "Noratrieb" +tags = ["rust", "language-design"] +keywords = ["design"] +description = "Bringing even more expressiveness to our items" +showFullContent = false +readingTime = true +hideComments = false +draft = false ++++ + +# The Inconsistency Problem + +Quite some time ago, I wrote [a blog post about the idea of `struct else`](./item-patterns-and-struct-else.md), which has been widely regarded as one of the most insightful pieces of Rust language design in the last few years[^insightful]. +If you have not read it, it's **strongly** recommended to first read it. + +But more recently, it has become clear that there are some serious problems around items that cause this to not work properly. + +This example non-deterministically results in an error about unresolved items. + +```rust +struct Test; +fn main() { + let x = Test; +} +``` + +``` +error[E0425]: cannot find value `Test` in this scope + --> :3:13 + | +3 | let x = Test; + | ^^^^ not found in this scope +``` + +This points at a concerning inconsistency in the Rust compiler. Is it a bug? Not really, it's just a lack of expressivity in the language. + +Let's go through this error step-by-step and see exactly why this happens. + +First, `struct Test` gets evaluated by the compiler. +It initializes the `Test` struct in the compiler, but the problem is that this initialization happens *asynchronously*. +This means that when we are compiling the `main` function, it might not have finished, causing the item to be missing. + +We now understand how this error comes to be, but how can it be fixed? + +## Asynchronous Programming + +Before we can understand the ideal solution to this problem, we need to first do a deep dive into asynchronous programming in general. + +The "async" in asynchronous programming is derived from the word "asynchronous". +Asynchronous programming refers to a particular style of programming where the execution flow is asynchronous. +This means that statements are executed asynchronously. +This asynchronousity can be difficult to work with, which is why it is generally tamed by awaiting. +Rust supports asynchronous programming with its `async` keyword, which is the shortened form of the word "asynchronous". +Rust has many keywords shortened like this, for example `fn` for "function" and `trait` for "traitor". + +Now that we know what asynchronous programming is, we can use our knowledge of it to tame our struct declarations. + +## Awaiting programming + +We can use the `.await` keyword in Rust to await an async function, taming its asynchronousity into something much easier to understand. +It's like if you tame a bear and make it meow. It will still eat you though. + +If we use the `.await` keyword on a struct declaration, we can tell the compiler to await the struct declaration, ensuring it will be finished initializing properly. + +```rust +struct Test.await; +fn main() { + let x = Test; // works!! +} +``` + +This is great, and fixes this long-standing issue with items in Rust. + +But we can take this further. + +## Generative Awaiting + +In Rust, we often want to generate code for some interface that is declared on the web. +It could be a W3C IDL, a Wayland Protocol XML or even a programming language specification like the Rust specification. + +Today, you need to download this file in a build script and generate the code from there. +This works great and is extremely flexible, but there are some security concerns with downloading a file during the build. +To avoid this, we should better integrate this with the language, and thanks to `.await` on structs we can. + +If we can use `.await` on anything, we can download a file right off the internet in our Rust source code! + +Combine this with our previous struct else logic, and we can generate code right in the items: + +```rust +impl std::net::http::Download<"https://noratrieb.dev/protocol.xml"> for Download {} +struct Download.await; + +struct Parsed { + name: String, + field_type: String, +} + +impl std::xml::Parse for Parsed {} + +struct Protocol { + [Parsed.name]: String, + my_field: [Parsed.field_type], +} else { + compile_error!("invalid xml"); +} +``` + +As we can see here, we now `.await` the declaration of the `Download` struct, which will automatically download a `protocol.xml` from my website[^protocolxml]. +We can then parse the XML using the novel `std::xml` module[^libxml], and then create a new struct declaration depending on the results of that. +If the XML is malformed, we can make use of `struct else` to error out in this case. + +## Conclusion + +We were able to harness the power of asynchronous programming and `.await` to not only fix a long-standing bug in the Rust language, but also significantly enhance the power of code generation in the Rust programming language. +This shows the flexibility of the programming style, which can be used for many other things, like implementing embedded control systems for killer drones or implementing a high performance webserver for a toy store. Or serving shitposts over the web. Soooo many use cases. + + +[^insightful]: Supposedly. People have said "still shocked this has not been stabilized yet" about this. +[^protocolxml]: It doesn't exist. Don't even try. No. +[^libxml]: It is suggested to use `libxml2` to implement this module. \ No newline at end of file From 71d67313425f3a91feaec973afbae18245287b0d Mon Sep 17 00:00:00 2001 From: Noratrieb <48135649+Noratrieb@users.noreply.github.com> Date: Thu, 9 Oct 2025 22:32:46 +0200 Subject: [PATCH 2/3] gaming --- .../posts/item-pattern-and-struct-await.md | 2 +- static/root/protocol.xml | 6269 +++++++++++++++++ 2 files changed, 6270 insertions(+), 1 deletion(-) create mode 100644 static/root/protocol.xml diff --git a/blog/content/posts/item-pattern-and-struct-await.md b/blog/content/posts/item-pattern-and-struct-await.md index facf44f..fd1f4bb 100644 --- a/blog/content/posts/item-pattern-and-struct-await.md +++ b/blog/content/posts/item-pattern-and-struct-await.md @@ -119,5 +119,5 @@ This shows the flexibility of the programming style, which can be used for many [^insightful]: Supposedly. People have said "still shocked this has not been stabilized yet" about this. -[^protocolxml]: It doesn't exist. Don't even try. No. +[^protocolxml]: meow. [^libxml]: It is suggested to use `libxml2` to implement this module. \ No newline at end of file diff --git a/static/root/protocol.xml b/static/root/protocol.xml new file mode 100644 index 0000000..4a645b9 --- /dev/null +++ b/static/root/protocol.xml @@ -0,0 +1,6269 @@ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 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+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + From 2dbefdfd686483bfd14173e232461b41a6943ccb Mon Sep 17 00:00:00 2001 From: Noratrieb <48135649+Noratrieb@users.noreply.github.com> Date: Thu, 9 Oct 2025 22:39:42 +0200 Subject: [PATCH 3/3] fix --- blog/content/posts/item-pattern-and-struct-await.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/blog/content/posts/item-pattern-and-struct-await.md b/blog/content/posts/item-pattern-and-struct-await.md index fd1f4bb..68b91b8 100644 --- a/blog/content/posts/item-pattern-and-struct-await.md +++ b/blog/content/posts/item-pattern-and-struct-await.md @@ -13,7 +13,7 @@ draft = false # The Inconsistency Problem -Quite some time ago, I wrote [a blog post about the idea of `struct else`](./item-patterns-and-struct-else.md), which has been widely regarded as one of the most insightful pieces of Rust language design in the last few years[^insightful]. +Quite some time ago, I wrote [a blog post about the idea of `struct else`](../item-patterns-and-struct-else), which has been widely regarded as one of the most insightful pieces of Rust language design in the last few years[^insightful]. If you have not read it, it's **strongly** recommended to first read it. But more recently, it has become clear that there are some serious problems around items that cause this to not work properly.