#framework #front-end #web #signal


A framework for building wasm front-end web application in Rust

1 unstable release

0.0.0 May 30, 2019

#11 in #wasm-framework

Custom license

1.5K SLoC


An experimental opinionated framework for frontend wasm app, base on futures-signals and wasm-bindgen. Mika is inspired by Dominator.

Compare to Dominator

Dominator Mika
Status "It is generally feature complete [...]" - Quoted from its README experimental. No single line of #[test] yet. It's just enough to run a partial version of TodoMVC (no routing, no persistent storage)
Base on Stdweb (stdweb is now also based on wasm-bindgen) wasm-bindgen directly
Separation of updating and rendering. By design, no! But can be easily added. Yes, it tries to help users separating the app-view-renderer and the app-state-updater. It's impossible to prevent users from insert app-state-mutating code into the render, but at least, Mika give its users a way to extract such code out of the renderer.
DOM contruction html!("div", {.class("some-class"), [...chilren...]}) Div::new().class("some-class").child(...).child(...)

Pros and cons

Both biggest advantage and biggest disadvantage are come from futures-signals.


  • futures-signals helps triggering the right parts of the code to response to a change in your app. (Contrast to virtual DOM approachs, which must walk through the whole virtual DOM to find diffs)


  • You must learn futures-signals.
  • Because of futures-signals, you find yourself fighting the borrow checker more often.

Build and serve

  • You must install Rust
  • rustup install nightly (futures-signals build with futures 0.3 which requires nightly)
  • rustup target add wasm32-unknown-unknown --toolchain=nightly (because we build for the web browser)
  • cargo install wasm-bindgen-cli (Mika build on top of wasm-bindgen)
  • cargo install simi-cli (Mika is similar to Simi)
  • git clone https://gitlab.com/limira-rs/mika.git
  • cd examples/counter
  • simi serve (yes, it's simi serve, because we use simi-cli)

Wait for the build to complete, then open your browser and visit http://localhost:8000/!


Not completed yet.

Minor notes:

  • You get signal/signal_vec from an instance of Mutable<T>/MutableVec<T> where T: Copy,
  • You get signal_cloned/signal_vec_cloned from an instance of Mutable<T>/MutableVec<T> where T: Clone,

Permitted content of an element

Mika tries to help you with the restrictions when adding child-elements to an element. If you find out that it does not allow a valid child or allow an invalid child (or any other bug), feel free to open an issue. Mika is unable to help on other restrictions such as descendant elements (child-elements in a child-element), child-element which is valid/invalid when with/without an attribute, order of child-elements...

There is still a bunch of TODO in src/dom/mod.rs, contributions are welcome.


~280K SLoC