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|
////
// IMPORTS ---------------------------------------------------------------------
import lustre/cmd
import lustre/element
import lustre/attribute
import gleam/result
// TYPES -----------------------------------------------------------------------
///
pub opaque type Program(state, action) {
Program(
init: #(state, Cmd(action)),
update: Update(state, action),
render: Render(state, action)
)
}
pub type Cmd(action) = cmd.Cmd(action)
pub type Element(action) = element.Element(action)
pub type Attribute(action) = attribute.Attribute(action)
pub type Error {
ElementNotFound
}
// These types aren't exposed, but they're just here to try and shrink the type
// annotations for `Program` and `program` a little bit. When generating docs,
// Gleam automatically expands type aliases so this is purely for the benefit of
// those reading the source.
//
type Update(state, action) = fn (state, action) -> #(state, Cmd(action))
type Render(state, action) = fn (state) -> Element(action)
// CONSTRUCTORS ----------------------------------------------------------------
/// Create a basic lustre program that just renders some element on the page.
/// Note that this doesn't mean the content is static! With `element.stateful`
/// you can still create components with local state.
///
/// Basic lustre programs don't have any *global* application state and so the
/// plumbing is a lot simpler. If you find yourself passing lot's state of state
/// around, you might want to consider using `application` instead.
///
pub fn basic (element: Element(any)) -> Program(Nil, any) {
let init = #(Nil, cmd.none())
let update = fn (_, _) { #(Nil, cmd.none()) }
let render = fn (_) { element }
Program(init, update, render)
}
/// Create a more complex application mimicing TEA – the Elm architecture. We
/// start with some initial `state`, a function to update that state, and then
/// a render function to derive our program's view from that state.
///
/// Events produced by elements are passed a `dispatch` function that can be
/// used to emit actions that trigger your `update` function to be called and
/// trigger a rerender.
///
pub fn application (init: #(state, Cmd(action)), update: Update(state, action), render: Render(state, action)) -> Program(state, action) {
Program(init, update, render)
}
// EFFECTS ---------------------------------------------------------------------
/// Once you have created a program with either `basic` or `application`, you
/// need to actually start it! This function will mount your program to the DOM
/// node that matches the query selector you provide.
///
/// If everything mounted OK, we'll get back a dispatch function that you can
/// call to send actions to your program and trigger an update.
///
pub fn start (program: Program(state, action), selector: String) -> Result(fn (action) -> Nil, Error) {
mount(program, selector)
|> result.replace_error(ElementNotFound)
}
external fn mount (program: Program(state, action), selector: String) -> Result(fn (action) -> Nil, Nil)
= "./ffi.mjs" "mount"
|
