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fission-macros

v0.10.0

Procedural macros for Fission actions, reducers, and ergonomic app authoring

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cargo add fission-macros

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Android

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iOS

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Linux

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macOS

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Windows

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Web

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Terminal

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Static site

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Server-rendered

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Package metadata

crates.io

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Documentation

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Repository

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License

MIT

Latest version

0.10.0

Downloads

1749

Last updated

2026-08-02T15:08:27.720794Z

fission-macros

Procedural macros for the Fission UI framework.

#[fission_component]

#[fission_component] marks a struct as a v2 authoring component. Ordinary fields remain props, while #[local_state] fields become typed accessors used from impl From<Component> for Widget.

use fission::prelude::*;

#[fission_component]
struct Counter {
    title: String,

    #[local_state(default = 0)]
    count: i32,
}

impl From<Counter> for Widget {
    fn from(counter: Counter) -> Widget {
        let count = counter.count();
        Text::new(format!("{}: {}", counter.title, count.get())).into()
    }
}

#[fission_reducer]

#[fission_reducer] is the recommended application-level shortcut for the common case where an action exists only to call one reducer.

use fission::prelude::*;

#[fission_reducer(Increment)]
fn increment(state: &mut CounterState) {
    state.count += 1;
}

This generates a real action type named Increment and a canonical reducer handler named increment. The generated action uses the reducer function visibility, so pub fn generates a public action and private functions generate private actions. You still bind it normally:

let on_press = with_reducer!(ctx, Increment, increment);

Payload parameters become tuple fields on the generated action:

#[fission_reducer(SetCount)]
fn set_count(state: &mut CounterState, value: i32) {
    state.count = value;
}

let action = with_reducer!(ctx, SetCount(10), set_count);

Reducers that need effects or input can keep an explicit final context parameter:

#[fission_reducer(SaveDraft)]
fn save_draft(state: &mut EditorState, ctx: &mut ReducerContext<EditorState>) {
    ctx.effects.app(SAVE_DRAFT, state.draft.clone());
}

For generated actions whose payloads cannot implement Eq, use no_eq:

#[fission_reducer(SetScale, no_eq)]
fn set_scale(state: &mut CanvasState, value: f32) {
    state.scale = value;
}

#[derive(FissionGlobalState)] and #[derive(FissionStateView)]

FissionGlobalState marks the root app state and generates a typed read-only view for build code. FissionStateView does the same for nested state structs.

use fission::prelude::*;

#[derive(Debug, Default, Clone, FissionGlobalState)]
struct ShopState {
    cart: CartState,
}

#[derive(Debug, Default, Clone, FissionStateView)]
struct CartState {
    items: Vec<String>,
}

let (_, view) = fission::build::current::<ShopState>();
let count = view.global().cart().items().map(|items| items.len()).get();

Use #[fission(skip_view)] on fields that should not appear in the generated view. The derive does not use runtime reflection or string lookup; generated methods call typed Rust accessors.

#[fission_action]

#[fission_action] remains the manual action definition tool. Use it when an action is shared by multiple reducers, exported as part of your public API, documented independently, or constructed in places where you want the action type spelled out explicitly.

use fission::prelude::*;

#[fission_action]
struct Increment;

fn increment(
    state: &mut CounterState,
    _action: Increment,
    _ctx: &mut ReducerContext<CounterState>,
) {
    state.count += 1;
}

This expands to the standard Fission action implementation plus the common serialization, debug, clone, and equality derives. The generated Action implementation computes the deterministic action ID from module_path!() and the Rust type name, then caches it with std::sync::OnceLock.

For payloads that cannot implement Eq, use:

#[fission_action(no_eq)]
struct SetScale(f32);

#[derive(Action)]

The derive macro remains available for lower-level crates that want to choose their own serialization and comparison derives explicitly. Application code should normally prefer #[fission_reducer] for one-reducer actions or #[fission_action] for manually declared actions.

README

fission-macros

Procedural macros for the Fission UI framework.

#[fission_component]

#[fission_component] marks a struct as a v2 authoring component. Ordinary fields remain props, while #[local_state] fields become typed accessors used from impl From<Component> for Widget.

use fission::prelude::*;

#[fission_component]
struct Counter {
    title: String,

    #[local_state(default = 0)]
    count: i32,
}

impl From<Counter> for Widget {
    fn from(counter: Counter) -> Widget {
        let count = counter.count();
        Text::new(format!("{}: {}", counter.title, count.get())).into()
    }
}

#[fission_reducer]

#[fission_reducer] is the recommended application-level shortcut for the common case where an action exists only to call one reducer.

use fission::prelude::*;

#[fission_reducer(Increment)]
fn increment(state: &mut CounterState) {
    state.count += 1;
}

This generates a real action type named Increment and a canonical reducer handler named increment. The generated action uses the reducer function visibility, so pub fn generates a public action and private functions generate private actions. You still bind it normally:

let on_press = with_reducer!(ctx, Increment, increment);

Payload parameters become tuple fields on the generated action:

#[fission_reducer(SetCount)]
fn set_count(state: &mut CounterState, value: i32) {
    state.count = value;
}

let action = with_reducer!(ctx, SetCount(10), set_count);

Reducers that need effects or input can keep an explicit final context parameter:

#[fission_reducer(SaveDraft)]
fn save_draft(state: &mut EditorState, ctx: &mut ReducerContext<EditorState>) {
    ctx.effects.app(SAVE_DRAFT, state.draft.clone());
}

For generated actions whose payloads cannot implement Eq, use no_eq:

#[fission_reducer(SetScale, no_eq)]
fn set_scale(state: &mut CanvasState, value: f32) {
    state.scale = value;
}

#[derive(FissionGlobalState)] and #[derive(FissionStateView)]

FissionGlobalState marks the root app state and generates a typed read-only view for build code. FissionStateView does the same for nested state structs.

use fission::prelude::*;

#[derive(Debug, Default, Clone, FissionGlobalState)]
struct ShopState {
    cart: CartState,
}

#[derive(Debug, Default, Clone, FissionStateView)]
struct CartState {
    items: Vec<String>,
}

let (_, view) = fission::build::current::<ShopState>();
let count = view.global().cart().items().map(|items| items.len()).get();

Use #[fission(skip_view)] on fields that should not appear in the generated view. The derive does not use runtime reflection or string lookup; generated methods call typed Rust accessors.

#[fission_action]

#[fission_action] remains the manual action definition tool. Use it when an action is shared by multiple reducers, exported as part of your public API, documented independently, or constructed in places where you want the action type spelled out explicitly.

use fission::prelude::*;

#[fission_action]
struct Increment;

fn increment(
    state: &mut CounterState,
    _action: Increment,
    _ctx: &mut ReducerContext<CounterState>,
) {
    state.count += 1;
}

This expands to the standard Fission action implementation plus the common serialization, debug, clone, and equality derives. The generated Action implementation computes the deterministic action ID from module_path!() and the Rust type name, then caches it with std::sync::OnceLock.

For payloads that cannot implement Eq, use:

#[fission_action(no_eq)]
struct SetScale(f32);

#[derive(Action)]

The derive macro remains available for lower-level crates that want to choose their own serialization and comparison derives explicitly. Application code should normally prefer #[fission_reducer] for one-reducer actions or #[fission_action] for manually declared actions.

Package metadata

crates.io

View package

Documentation

Not provided

Repository

Open link

License

MIT

Latest version

0.10.0

Downloads

1749

Last updated

2026-08-02T15:08:27.720794Z