-module(lustre). -compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch]). -export([application/3, element/1, simple/3, component/4, start_actor/2, start_server_component/2, register/2, dispatch/1, shutdown/0, is_browser/0, start/3, is_registered/1]). -export_type([app/3, client_spa/0, server_component/0, error/0]). -if(?OTP_RELEASE >= 27). -define(MODULEDOC(Str), -moduledoc(Str)). -define(DOC(Str), -doc(Str)). -else. -define(MODULEDOC(Str), -compile([])). -define(DOC(Str), -compile([])). -endif. ?MODULEDOC( " Lustre is a framework for rendering Web applications and components using\n" " Gleam. This module contains the core API for constructing and communicating\n" " with Lustre applications. If you're new to Lustre or frontend development in\n" " general, make sure you check out the [examples](https://github.com/lustre-labs/lustre/tree/main/examples)\n" " or the [quickstart guide](./guide/01-quickstart.html) to get up to speed!\n" "\n" " Lustre currently has three kinds of application:\n" "\n" " 1. A client-side single-page application: think Elm or React or Vue. These\n" " are applications that run in the client's browser and are responsible for\n" " rendering the entire page.\n" "\n" " 2. A client-side component: an encapsulated Lustre application that can be\n" " rendered inside another Lustre application as a Web Component. Communication\n" " happens via attributes and event listeners, like any other encapsulated\n" " HTML element.\n" "\n" " 3. A server component. These are applications that run anywhere Gleam runs\n" " and communicate with any number of connected clients by sending them\n" " patches to apply to their DOM.\n" "\n" " There are two pieces to a server component: the main server component\n" " runtime that contains your application logic, and a client-side runtime\n" " that listens for patches over a WebSocket and applies them to the DOM.\n" "\n" " The server component runtime can run anywhere Gleam does, but the\n" " client-side runtime must be run in a browser. To use it either render the\n" " [provided script element](./lustre/server_component.html#script) or use the script files\n" " from Lustre's `priv/` directory directly.\n" "\n" " No matter where a Lustre application runs, it will always follow the same\n" " Model-View-Update architecture. Popularised by Elm (where it is known as The\n" " Elm Architecture), this pattern has since made its way into many other\n" " languages and frameworks and has proven to be a robust and reliable way to\n" " build complex user interfaces.\n" "\n" " There are three main building blocks to the Model-View-Update architecture:\n" "\n" " - A `Model` that represents your application's state and an `init` function\n" " to create it.\n" "\n" " - A `Msg` type that represents all the different ways the outside world can\n" " communicate with your application and an `update` function that modifies\n" " your model in response to those messages.\n" "\n" " - A `view` function that renders your model to HTML, represented as an\n" " `Element`.\n" "\n" " To see how those pieces fit together, here's a little diagram:\n" "\n" " ```text\n" " +--------+\n" " | |\n" " | update |\n" " | |\n" " +--------+\n" " ^ |\n" " | |\n" " Msg | | #(Model, Effect(Msg))\n" " | |\n" " | v\n" " +------+ +------------------------+\n" " | | #(Model, Effect(Msg)) | |\n" " | init |------------------------>| Lustre Runtime |\n" " | | | |\n" " +------+ +------------------------+\n" " ^ |\n" " | |\n" " Msg | | Model\n" " | |\n" " | v\n" " +--------+\n" " | |\n" " | view |\n" " | |\n" " +--------+\n" " ```\n" "\n" " The `Effect` type here encompasses things like HTTP requests and other kinds\n" " of communication with the \"outside world\". You can read more about effects\n" " and their purpose in the [`effect`](./effect.html) module.\n" "\n" " For many kinds of apps, you can take these three building blocks and put\n" " together a Lustre application capable of running *anywhere*. Because of that,\n" " we like to describe Lustre as a **universal framework**.\n" "\n" " ## Guides\n" "\n" " A number of guides have been written to teach you how to use Lustre to build\n" " different kinds of applications. If you're just getting started with Lustre\n" " or frontend development, we recommend reading through them in order:\n" "\n" " - [`01-quickstart`](/guide/01-quickstart.html)\n" "\n" " This list of guides is likely to grow over time, so be sure to check back\n" " every now and then to see what's new!\n" "\n" " ## Examples\n" "\n" " If you prefer to learn by seeing and adapting existing code, there are also\n" " a number of examples in the [Lustre GitHub repository](https://github.com/lustre-labs/lustre)\n" " that each demonstrate a different concept or idea:\n" "\n" " - [`01-hello-world`](https://github.com/lustre-labs/lustre/tree/main/examples/01-hello-world)\n" " - [`02-interactivity`](https://github.com/lustre-labs/lustre/tree/main/examples/02-interactivity)\n" " - [`03-controlled-inputs`](https://github.com/lustre-labs/lustre/tree/main/examples/03-controlled-inputs)\n" " - [`04-custom-event-handlers`](https://github.com/lustre-labs/lustre/tree/main/examples/04-custom-event-handlers)\n" " - [`05-http-requests`](https://github.com/lustre-labs/lustre/tree/main/examples/05-http-requests)\n" " - [`06-custom-effects`](https://github.com/lustre-labs/lustre/tree/main/examples/06-custom-effects)\n" "\n" " This list of examples is likely to grow over time, so be sure to check back\n" " every now and then to see what's new!\n" "\n" " ## Companion libraries\n" "\n" " While this package contains the runtime and API necessary for building and\n" " rendering applications, there is also a small collection of companion libraries\n" " built to make building Lustre applications easier:\n" "\n" " - [lustre/ui](https://github.com/lustre-labs/ui) is a collection of pre-designed\n" " elements and design tokens for building user interfaces with Lustre.\n" "\n" " - [lustre/ssg](https://github.com/lustre-labs/ssg) is a simple static site\n" " generator that you can use to produce static HTML documents from your Lustre\n" " applications.\n" "\n" " Both of these packages are heavy works in progress: any feedback or contributions\n" " are very welcome!\n" "\n" "\n" " ## Getting help\n" "\n" " If you're having trouble with Lustre or not sure what the right way to do\n" " something is, the best place to get help is the [Gleam Discord server](https://discord.gg/Fm8Pwmy).\n" " You could also open an issue on the [Lustre GitHub repository](https://github.com/lustre-labs/lustre/issues).\n" "\n" " While our docs are still a work in progress, the official [Elm guide](https://guide.elm-lang.org)\n" " is also a great resource for learning about the Model-View-Update architecture\n" " and the kinds of patterns that Lustre is built around.\n" "\n" " ## Contributing\n" "\n" " The best way to contribute to Lustre is by building things! If you've built\n" " something cool with Lustre you want to share then please share it on the\n" " `#sharing` channel in the [Gleam Discord server](https://discord.gg/Fm8Pwmy).\n" " You can also tag Hayleigh on Twitter [@hayleigh-dot-dev](https://twitter.com/hayleighdotdev)\n" " or on BlueSky [@hayleigh.dev](https://bsky.app/profile/hayleigh.dev).\n" "\n" " If you run into any issues or have ideas for how to improve Lustre, please\n" " open an issue on the [Lustre GitHub repository](https://github.com/lustre-labs/lustre/issues).\n" " Fixes and improvements to the documentation are also very welcome!\n" "\n" " Finally, if you'd like, you can support the project through\n" " [GitHub Sponsors](https://github.com/sponsors/hayleigh-dot-dev). Sponsorship\n" " helps fund the copious amounts of coffee that goes into building and maintaining\n" " Lustre, and is very much appreciated!\n" "\n" ). -opaque app(QST, QSU, QSV) :: {app, fun((QST) -> {QSU, lustre@effect:effect(QSV)}), fun((QSU, QSV) -> {QSU, lustre@effect:effect(QSV)}), fun((QSU) -> lustre@internals@vdom:element(QSV)), gleam@option:option(gleam@dict:dict(binary(), fun((gleam@dynamic:dynamic_()) -> {ok, QSV} | {error, list(gleam@dynamic:decode_error())})))}. -type client_spa() :: any(). -type server_component() :: any(). -type error() :: {actor_error, gleam@otp@actor:start_error()} | {bad_component_name, binary()} | {component_already_registered, binary()} | {element_not_found, binary()} | not_a_browser | not_erlang. -file("src/lustre.gleam", 328). ?DOC( " A complete Lustre application that follows the Model-View-Update architecture\n" " and can handle side effects like HTTP requests or querying the DOM. Most real\n" " Lustre applications will use this constructor.\n" "\n" " To learn more about effects and their purpose, take a look at the\n" " [`effect`](./lustre/effect.html) module or the\n" " [HTTP requests example](https://github.com/lustre-labs/lustre/tree/main/examples/05-http-requests).\n" ). -spec application( fun((QTO) -> {QTP, lustre@effect:effect(QTQ)}), fun((QTP, QTQ) -> {QTP, lustre@effect:effect(QTQ)}), fun((QTP) -> lustre@internals@vdom:element(QTQ)) ) -> app(QTO, QTP, QTQ). application(Init, Update, View) -> {app, Init, Update, View, none}. -file("src/lustre.gleam", 293). ?DOC( " An element is the simplest type of Lustre application. It renders its contents\n" " once and does not handle any messages or effects. Often this type of application\n" " is used for folks just getting started with Lustre on the frontend and want a\n" " quick way to get something on the screen.\n" "\n" " Take a look at the [`simple`](#simple) application constructor if you want to\n" " build something interactive.\n" "\n" " > **Note**: Just because an element doesn't have its own update loop, doesn't\n" " > mean its content is always static! An element application may render a client\n" " > or server component that has its own encapsulated update loop!\n" ). -spec element(lustre@internals@vdom:element(QTC)) -> app(nil, nil, QTC). element(Html) -> Init = fun(_) -> {nil, lustre@effect:none()} end, Update = fun(_, _) -> {nil, lustre@effect:none()} end, View = fun(_) -> Html end, application(Init, Update, View). -file("src/lustre.gleam", 309). ?DOC( " A `simple` application has the basic Model-View-Update building blocks present\n" " in all Lustre applications, but it cannot handle effects. This is a great way\n" " to learn the basics of Lustre and its architecture.\n" "\n" " Once you're comfortable with the Model-View-Update loop and want to start\n" " building more complex applications that can communicate with the outside world,\n" " you'll want to use the [`application`](#application) constructor instead.\n" ). -spec simple( fun((QTH) -> QTI), fun((QTI, QTJ) -> QTI), fun((QTI) -> lustre@internals@vdom:element(QTJ)) ) -> app(QTH, QTI, QTJ). simple(Init, Update, View) -> Init@1 = fun(Flags) -> {Init(Flags), lustre@effect:none()} end, Update@1 = fun(Model, Msg) -> {Update(Model, Msg), lustre@effect:none()} end, application(Init@1, Update@1, View). -file("src/lustre.gleam", 354). ?DOC( " A `component` is a type of Lustre application designed to be embedded within\n" " another application and has its own encapsulated update loop. This constructor\n" " is almost identical to the [`application`](#application) constructor, but it\n" " also allows you to specify a dictionary of attribute names and decoders.\n" "\n" " When a component is rendered in a parent application, it can receive data from\n" " the parent application through HTML attributes and properties just like any\n" " other HTML element. This dictionary of decoders allows you to specify how to\n" " decode those attributes into messages your component's update loop can handle.\n" "\n" " **Note**: Lustre components are conceptually a lot \"heavier\" than components\n" " in frameworks like React. They should be used for more complex UI widgets\n" " like a combobox with complex keyboard interactions rather than simple things\n" " like buttons or text inputs. Where possible try to think about how to build\n" " your UI with simple view functions (functions that return [Elements](./lustre/element.html#Element))\n" " and only reach for components when you really need to encapsulate that update\n" " loop.\n" ). -spec component( fun((QTX) -> {QTY, lustre@effect:effect(QTZ)}), fun((QTY, QTZ) -> {QTY, lustre@effect:effect(QTZ)}), fun((QTY) -> lustre@internals@vdom:element(QTZ)), gleam@dict:dict(binary(), fun((gleam@dynamic:dynamic_()) -> {ok, QTZ} | {error, list(gleam@dynamic:decode_error())})) ) -> app(QTX, QTY, QTZ). component(Init, Update, View, On_attribute_change) -> {app, Init, Update, View, {some, On_attribute_change}}. -file("src/lustre.gleam", 387). -spec do_start(app(QUT, any(), QUV), binary(), QUT) -> {ok, fun((lustre@internals@runtime:action(QUV, client_spa())) -> nil)} | {error, error()}. do_start(_, _, _) -> {error, not_a_browser}. -file("src/lustre.gleam", 444). -spec do_start_actor(app(QVY, any(), QWA), QVY) -> {ok, gleam@erlang@process:subject(lustre@internals@runtime:action(QWA, server_component()))} | {error, error()}. do_start_actor(App, Flags) -> On_attribute_change = gleam@option:unwrap( erlang:element(5, App), maps:new() ), _pipe = (erlang:element(2, App))(Flags), _pipe@1 = lustre@internals@runtime:start( _pipe, erlang:element(3, App), erlang:element(4, App), On_attribute_change ), gleam@result:map_error(_pipe@1, fun(Field@0) -> {actor_error, Field@0} end). -file("src/lustre.gleam", 431). ?DOC( " Start an application as a server component specifically for the Erlang target.\n" " Instead of receiving a callback on successful start, this function returns\n" " a [`Subject`](https://hexdocs.pm/gleam_erlang/gleam/erlang/process.html#Subject)\n" "\n" "\n" " **Note**: This function is only meaningful on the Erlang target. Attempts to\n" " call it on the JavaScript will result in the `NotErlang` error. If you're running\n" " a Lustre server component on Node or Deno, use [`start_server_component`](#start_server_component)\n" " instead.\n" ). -spec start_actor(app(QVN, any(), QVP), QVN) -> {ok, gleam@erlang@process:subject(lustre@internals@runtime:action(QVP, server_component()))} | {error, error()}. start_actor(App, Flags) -> do_start_actor(App, Flags). -file("src/lustre.gleam", 413). ?DOC( " Start an application as a server component. This runs in a headless mode and\n" " doesn't render anything to the DOM. Instead, multiple clients can be attached\n" " using the [`add_renderer`](#add_renderer) action.\n" "\n" " If a server component starts successfully, this function will return a callback\n" " that can be used to send actions to the component runtime.\n" "\n" " A server component will keep running until the program is terminated or the\n" " [`shutdown`](#shutdown) action is sent to it.\n" "\n" " **Note**: Users running their application on the BEAM should use [`start_actor`](#start_actor)\n" " instead to make use of Gleam's OTP abstractions.\n" ). -spec start_server_component(app(QVD, any(), QVF), QVD) -> {ok, fun((lustre@internals@runtime:action(QVF, server_component())) -> nil)} | {error, error()}. start_server_component(App, Flags) -> gleam@result:map( start_actor(App, Flags), fun(Runtime) -> fun(_capture) -> gleam@otp@actor:send(Runtime, _capture) end end ). -file("src/lustre.gleam", 477). ?DOC( " Register a Lustre application as a Web Component. This lets you render that\n" " application in another Lustre application's view or use it as a Custom Element\n" " outside of Lustre entirely.The provided application can only have `Nil` flags\n" " because there is no way to provide an initial value for flags when using a\n" " Custom Element!\n" "\n" " The second argument is the name of the Custom Element. This is the name you'd\n" " use in HTML to render the component. For example, if you register a component\n" " with the name `my-component`, you'd use it in HTML by writing ``\n" " or in Lustre by rendering `element(\"my-component\", [], [])`.\n" "\n" " **Note**: There are [some rules](https://developer.mozilla.org/en-US/docs/Web/API/CustomElementRegistry/define#valid_custom_element_names)\n" " for what names are valid for a Custom Element. The most important one is that\n" " the name *must* contain a hypen so that it can be distinguished from standard\n" " HTML elements.\n" "\n" " **Note**: This function is only meaningful when running in the browser and will\n" " produce a `NotABrowser` error if called anywhere else. For server contexts,\n" " you can render a Lustre server component using [`start_server_component`](#start_server_component)\n" " or [`start_actor`](#start_actor) instead.\n" ). -spec register(app(nil, any(), any()), binary()) -> {ok, nil} | {error, error()}. register(_, _) -> {error, not_a_browser}. -file("src/lustre.gleam", 490). ?DOC( " Dispatch a message to a running application's `update` function. This can be\n" " used as a way for the outside world to communicate with a Lustre app without\n" " the app needing to initiate things with an effect.\n" "\n" " Both client SPAs and server components can have messages sent to them using\n" " the `dispatch` action.\n" ). -spec dispatch(QWQ) -> lustre@internals@runtime:action(QWQ, any()). dispatch(Msg) -> {dispatch, Msg}. -file("src/lustre.gleam", 499). ?DOC( " Instruct a running application to shut down. For client SPAs this will stop\n" " the runtime and unmount the app from the DOM. For server components, this will\n" " stop the runtime and prevent any further patches from being sent to connected\n" " clients.\n" ). -spec shutdown() -> lustre@internals@runtime:action(any(), any()). shutdown() -> shutdown. -file("src/lustre.gleam", 514). ?DOC( " Gleam's conditional compilation makes it possible to have different implementations\n" " of a function for different targets, but it's not possible to know what runtime\n" " you're targeting at compile-time.\n" "\n" " This is problematic if you're using server components with a JavaScript\n" " backend because you'll want to know whether you're currently running on your\n" " server or in the browser: this function tells you that!\n" ). -spec is_browser() -> boolean(). is_browser() -> false. -file("src/lustre.gleam", 377). ?DOC( " Start a constructed application as a client-side single-page application (SPA).\n" " This is the most typical way to start a Lustre application and will *only* work\n" " in the browser\n" "\n" " The second argument is a [CSS selector](https://developer.mozilla.org/en-US/docs/Web/API/Document/querySelector)\n" " used to locate the DOM element where the application will be mounted on to.\n" " The most common selectors are `\"#app\"` to target an element with an id of `app`\n" " or `[data-lustre-app]` to target an element with a `data-lustre-app` attribute.\n" "\n" " The third argument is the starting data for the application. This is passed\n" " to the application's `init` function.\n" ). -spec start(app(QUJ, any(), QUL), binary(), QUJ) -> {ok, fun((lustre@internals@runtime:action(QUL, client_spa())) -> nil)} | {error, error()}. start(App, Selector, Flags) -> gleam@bool:guard( not is_browser(), {error, not_a_browser}, fun() -> do_start(App, Selector, Flags) end ). -file("src/lustre.gleam", 523). ?DOC( " Check if the given component name has already been registered as a Custom\n" " Element. This is particularly useful in contexts where _other web components_\n" " may have been registered and you must avoid collisions.\n" ). -spec is_registered(binary()) -> boolean(). is_registered(_) -> false.