Reactivity: Conditions

show()

Displays components once a certain condition is met.

type Molecule<T> = () -> T
type Derivable<T> = (Molecule<T>) | T

function show<T>(input: Derivable<unknown>, component: () -> T): T?
function show<T, U>(input: Derivable<unknown>, component: () -> T, fallback: () -> U): (T | U)?

Parameters

• input: A derivable that returns a truthy value that determines what component to display.

• component: A callback that returns a component that will display if input returns true.

• optional fallback: A callback that returns a component that will display if input returns false.

Returns

1. If the result from input is set to nil, the output of show is nil.
2. If the result from input is set to true, show will return the result from component.
3. If fallback is enabled and the result from input is set to false, show will return the result from fallback.

Example:

local source = flec(true)

local function truth_text()
    return new "TextLabel" {
        Text = "The other text is a liar..."
    }
end

local function lie_text()
    return new "TextLabel" {
        Text = "The other text sure ain't a truther!"
    }
end

local function app()
    return new "ScreenGui" {
        show(source, truth_text, lie_text)
    }
end

mount(app, Players.LocalPlayer.PlayerGui)

task.delay(2, function()
    source(false)
end)

switch()

Displays a component out of a list of components given an input and a mapping table.

type Molecule<T> = () -> T
type Derivable<T> = (Molecule<T>) | T

function switch<K, V>(source: Derivable<K>): (map: Map<K, () -> V>): () -> V?

Parameters

• source: A derivable that returns a value that can be inputed onto the map to get a component constructor. This component is then ran inside a stable scope. Each time source updates, previous scopes get destroyed.

Returns

switch returns a read-only flec containing an instance of the current component shown, or nil if no component is currently shown.

Example:

local input = flec(false)

local function truth_text()
    return new "TextLabel" {
        Text = "The other text is a liar..."
    }
end

local function lie_text()
    return new "TextLabel" {
        Text = "The other text sure ain't a truther!"
    }
end

local text = switch(input) {
    [true] = truth_text,
    [false] = liar_text,
}

local function app()
    return new "ScreenGui" {
        text
    }
end

mount(app, Players.LocalPlayer.PlayerGui)

task.delay(2, function()
    source(false)
end)