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import gleam/option.{type Option, None, Some}
import lustre
import lustre/attribute
import lustre/effect.{type Effect}
import lustre/element.{type Element}
import lustre/event
// These examples are written with `lustre/ui` in mind. They'll work regardless,
// but to see what `lustre/ui` can do make sure to run each of these examples with
// the `--use-example-styles` flag:
//
// $ gleam run -m lustre/dev start --use-example-styles
//
// In your own apps, make sure to add the `lustre/ui` dependency and include the
// stylesheet somewhere.
import lustre/ui
// MAIN ------------------------------------------------------------------------
pub fn main() {
let app = lustre.application(init, update, view)
let assert Ok(_) = lustre.start(app, "#app", Nil)
}
// MODEL -----------------------------------------------------------------------
type Model {
Model(message: Option(String))
}
fn init(_) -> #(Model, Effect(Msg)) {
#(Model(message: None), read_localstorage("message", GotMessage))
}
// UPDATE ----------------------------------------------------------------------
pub opaque type Msg {
GotInput(String)
GotMessage(Result(String, Nil))
}
fn update(model: Model, msg: Msg) -> #(Model, Effect(Msg)) {
case msg {
GotInput(input) -> #(
Model(message: Some(input)),
write_localstorage("message", input),
)
GotMessage(Ok(message)) -> #(Model(message: Some(message)), effect.none())
GotMessage(Error(_)) -> #(model, effect.none())
}
}
fn read_localstorage(
key: String,
to_msg: fn(Result(String, Nil)) -> msg,
) -> Effect(msg) {
effect.from(fn(dispatch) {
do_read_localstorage(key)
|> to_msg
|> dispatch
})
}
@external(javascript, "./app.ffi.mjs", "read_localstorage")
fn do_read_localstorage(_key: String) -> Result(String, Nil) {
Error(Nil)
}
fn write_localstorage(key: String, value: String) -> Effect(msg) {
effect.from(fn(_) { do_write_localstorage(key, value) })
}
@external(javascript, "./app.ffi.mjs", "write_localstorage")
fn do_write_localstorage(_key: String, _value: String) -> Nil {
Nil
}
// VIEW ------------------------------------------------------------------------
fn view(model: Model) -> Element(Msg) {
let styles = [#("width", "100vw"), #("height", "100vh")]
let message = option.unwrap(model.message, "")
ui.centre(
[attribute.style(styles)],
ui.field(
[],
[],
ui.input([attribute.value(message), event.on_input(GotInput)]),
[element.text("Type a message and refresh the page")],
),
)
}
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