apps.md

apps

module A simple, uni-directional data flow architecture. All global functions inside this module can be used on all statefuls.

Example

We start by defining a model. A model is a record with an initial state and an update function. The update function takes a state and a message and returns an Update record.

In this example we have a simple counter model.

import apps

enum Message {
    data Inc
    data Dec
}

let model = apps.defineModel 0, { state, msg =>
    with msg, type apps.Message {
        Inc: { _ => apps.Update state + 1, Nil },
        Dec: { _ => apps.Update state - 1, Nil },
    }
}

let view = apps.render model, { dispatch, state =>
    print strings.join ["Current state: ", state]
}

import tests

tests.test "apps", { fail =>
    apps.send view, Inc

    unless (apps.currentState view) == 1, fail "should be 1"
}

• data Batch
• enum Command
• enum Message
• data Model
• data Quit
• enum Stateful
• data Store
• data Update
• data View
• func currentState stateful
• func defineModel initial, update
• func render model, view
• func send stateful, cmd
• func storeFrom model
• func subscribe observer, stateful
• func update stateful, msg

Batch

data A batch of Commands

Properties

• cmds

Command

enum A command can be either a message, a batch of messages or an async message.

Cases

• Async
• Batch
• Message

Message

enum The messages any stateful can handle. prelude.Nil and prelude.None are used to indicate that no message should be send. prelude.Any is used to indicate that any message should be send.

Cases

• Quit
• Nil
• None
• Any

Model

data A model defines the abstract and underlaying behaviour of a stateful. It has an initial state and an update function.

Properties

• initial - The initial state
• update state, msg - The update function. Takes a state and a message and returns an Update record.

Quit

data Quits the whole program

Stateful

enum Represents all statefuls like Stores and Views.

Cases

• Store
• View

Store

data A stateful which holds a state and can be observed.

Properties

• model - The Model
• states - A rx.Variable of a State
• observers - A rx.Variable of functions to be notified.

Update

data The update record includes the new state after applying a message and a command to be send to the store.

Properties

• state - The new state
• cmd - A command to be send to the store.

View

data A stateful which renders a view. The result of the view differs from use case to use case.

Whenever you have one representation of your whole state, the View is the right choice.

Properties

• store - The underlying and observed store.
• view dispatch, state - A function which renders the current state. Might dispatch cmd.

currentState

func currentState stateful

Returns the current state of a stateful.

defineModel

func defineModel initial, update

Creates a new model.

render

func render model, view

Creates a new view by rendering a store on every change.

send

func send stateful, cmd

Sends an eventually async Command to a stateful. Always returns a Result.

storeFrom

func storeFrom model

Creates a new store from a model. This essentially adds dynamic behaviour to a model.

subscribe

func subscribe observer, stateful

Observes changes of a stateful.

update

func update stateful, msg

Directly applies a message to a stateful.