A Rust framework for creating web apps
The best place to learn is the guide - this readme is an excerpt from it.
This framework requires you to install Rust - This will enable the CLI commands below:
You'll need a recent version of Rust: rustup update
The wasm32-unknown-unknown target: rustup target add wasm32-unknown-unknown
And wasm-bindgen: cargo install wasm-bindgen-cli
To start, clone This quickstart repo,
run build.sh or build.ps1 in a terminal, then start a dev server that supports WASM.
For example, with Python installed, run python serve.py.
(Linux users may need to run python3 serve.py.)
Once you change your package name, you'll
need to tweak the html file and build script, as described below.
Or, create a new lib with Cargo: cargo new --lib appname. Here and everywhere it appears in this guide,
appname should be replaced with the name of your app.
If not using the quickstart repo, create an Html file that loads your app's compiled module, and provides an element with id to load the framework into. It also needs the following code to load your WASM module - Ie, the body should contain this:
```html
```
The quickstart repo includes this file, but you will need to rename the two
occurances of appname. (If your project name has a hyphen, use an underscore instead here) You will eventually need to modify this file to
change the page's title, add a description, favicon, stylesheet etc.
Cargo.toml, which is a file created by Cargo that describes your app, needs wasm-bindgen, web-sys, and
seed added as depdendencies,
and crate-type
of "cdylib". (The version in the quickstart repo has these set up already) Example:
```toml [package] name = "appname" version = "0.1.0" authors = ["Your Name email@address.com"] edition = "2018"
[lib] crate-type = ["cdylib"]
[dependencies] seed = "^0.1.6" wasm-bindgen = "^0.2.29" web-sys = "^0.3.6"
serde = "^1.0.80" serdederive = "^1.0.80" serdejson = "1.0.33" ```
Here's an example demonstrating structure and syntax; it can be found in working form
under examples/counter. Descriptions of its parts are in the
Guide section below. Its structure follows The Elm Architecture.
lib.rs: ```rust
extern crate seed; use seed::prelude::; use wasm_bindgen::prelude::;
// Model
struct Model { count: i32, whatwecount: String }
// Setup a default here, for initialization later. impl Default for Model { fn default() -> Self { Self { count: 0, whatwecount: "click".into() } } }
// Update
enum Msg { Increment, Decrement, ChangeWWC(String), }
/// The sole source of updating the model; returns a fresh one. fn update(msg: Msg, model: Model) -> Model { match msg { Msg::Increment => Model {count: model.count + 1, ..model}, Msg::Decrement => Model {count: model.count - 1, ..model}, Msg::ChangeWWC(whatwecount) => Model {whatwecount, ..model } } }
// View
/// A simple component.
fn success_level(clicks: i32) -> El
/// The top-level component we pass to the virtual dom. Must accept a ref to the model as its
/// only argument, and output a single El.
fn view(model: Model) -> El
// Attrs, Style, Events, and children may be defined separately.
let outer_style = style!{
"display" => "flex";
"flex-direction" => "column";
"text-align" => "center"
};
div![ outer_style,
h1![ "The Grand Total" ],
div![
style!{
// Example of conditional logic in a style.
"color" => if model.count > 4 {"purple"} else {"gray"};
// When passing numerical values to style!, "px" is implied.
"border" => "2px solid #004422"; "padding" => 20
},
// We can use normal Rust code and comments in the view.
h3![ format!("{} {}{} so far", model.count, model.what_we_count, plural) ],
button![ simple_ev("click", Msg::Increment), "+" ],
button![ simple_ev("click", Msg::Decrement), "-" ],
// Optionally-displaying an element
if model.count >= 10 { h2![ style!{"padding" => 50}, "Nice!" ] } else { seed::empty() }
],
success_level(model.count), // Incorporating a separate component
h3![ "What precisely is it we're counting?" ],
input![ attrs!{"value" => model.what_we_count}, input_ev("input", Msg::ChangeWWC) ]
]
}
pub fn render() { // The final parameter is an optional routing map. seed::run(Model::default(), update, view, "main", None); } ``` For truly minimimal example, see lib.rs in the quickstart repo
To build your app, create a pkg subdirectory, and run the following two commands:
cargo build --target wasm32-unknown-unknown
and
wasm-bindgen target/wasm32-unknown-unknown/debug/appname.wasm --no modules --out-dir ./pkg
where appname is replaced with your app's name. This compiles your code in the target
folder, and populates the pkg folder with your WASM module, a Typescript definitions file,
and a Javascript file used to link your module from HTML.
You may wish to create a build script with these two lines. (build.sh for Linux; build.ps1 for Windows).
The Quickstart repo includes these, but you'll still need to do the rename. You can then use
./build.sh or .\build.ps1 If you run into permission errors on build.sh, try this command
to allow executing the file:chmod +x build.sh.
For development, you can view your app using a shimmed Python dev server described above.
(Set up this mime-type shim
from the quickstart repo, and run python serve.py).
For details, reference the wasm-bindgen documention. In the future, I'd like the build script and commands above to be replaced by wasm-pack.
To run an example located in the examples folder, navigate to that folder in a terminal,
run the build script for your system (build.sh or build.ps1), then start a dev server
as described above. Note that if you copy an example to a separate folder, you'll need
to edit its Cargo.toml to point to the package on crates.io instead of locally: Ie replace
seed = { path = "../../" with seed = "^0.1.0", and in the build script, remove the leading ../../ on the second
line.
Learning the syntax, creating a project, and building it should be easy - regardless of your familiarity with Rust.
Complete documentation that always matches the current version. Getting examples working, and starting a project should be painless, and require nothing beyond this guide.
Expressive, flexible vew syntax that's easy to read and write.
This project takes a different approach to describing how to display DOM elements than others. It neither uses completely natural (ie macro-free) Rust code, nor an HTML-like abstraction (eg JSX or templates). My intent is to make the code close to natural Rust, while streamlining the syntax in a way suited for creating a visual layout with minimal repetition. The macros used here are thin wrappers for constructors, and don't conceal much. Specifically, the element-creation macros allow for accepting a variable number of arguments, and the attrs/style marcros are essentially HashMap literals, with wrappers that let el macros know how to distinguish them.
The lack of resemblance to HTML be offputting, but the learning curve is shallow, and I think the macro syntax used to create elements, attributes etc is close-enough to normal Rust syntax that it's easy to reason about how the code should come together, without compartmentalizing it into logic code and display code. This lack of separation in particlar is a subjective, controversial decision, but I think the benefits are worth it.
The todomvc example is an implementation of the TodoMVC project, which has example code in my frameworks that do the same thing. Compare the example in this project to one on that page that uses a framework you're familiar with.
This project is strongly influenced by Elm, React, and Redux. The overall layout of Seed apps mimicks that of The Elm Architecture.
My goal is for this to be easy to pick up from looking at a tutorial or documentation, regardless of your
level of experience with Rust. I'm distinguising this package through clear examples
and documentation (see goals above), and using wasm-bindgen internally. I started this
project after being unable to get existing frameworks to work
due to lack of documented examples, and inconsistency between documentation and
published versions. My intent is for anyone who's proficient in a frontend
framework to get a standalone app working in the browser within a few minutes, using just the
quickstart guide.
Seed approaches HTML-display syntax differently from existing packages: rather than use an HTML-like markup similar to JSX, it uses Rust builtin types, thinly-wrapped by a macro for each DOM element. This decision may not appeal to everyone, but I think it integrates more naturally with the language.
You may prefer writing in Rust, and using packages from Cargo vis npm. Getting started with this framework will, in most cases be faster, and require less config and setup overhead than with JS frameworks. You like the advantages of compile-time error-checking.
You may choose this approach over Elm if you're already comfortable with Rust, want the performance benefits, or don't want to code business logic in a purely-functional langauge.
Compared with React, you may appreciate the consistency of how to write apps: There's no distinction between logic and display code; no restrictions on comments; no distinction between components and normal functions. The API is flexible, and avoids OOP boilerplate.
I also hope that config, building, and dependency-management is cleaner with Cargo and wasm-bindgen than with npm.
High-level CSS-grid/Flexbox API ?
Text renders above children instead of below