Macros

Macros lets you define a snippet of RSML which can be reused throughout your styles. You can import them from another Style Sheet via the @derive declaration.

They can be defined via the macro declaration:

@macro MyCoolMacro {
    Size = udim2 (200px, 100px);
    Position = udim2 (.5, .5);
}

Macros can be given arguments which can be referenced via a & prefix

@macro MyCoolMacro (&size) {
    Size = &size;
    Position = udim2 (.5, .5);
}

Return Context

By default macro's must return fully qualified expression(s) or block(s). But they can be customized to return a selector or a datatype by defining a return context.

Name	Context
Construct	Must return a fully qualified expression(s) or block(s).
Datatype	Must return a datatype.
Selector	Must return a selector.

@macro MyCoolMacro (&arg) -> Datatype {
    rgb (35, 24, 31)
}

@macro MyCoolMacro (&arg) -> Selector {
    ::TextButton
}

Calling Macros

A macro can be called by referencing its name with a ! suffix. All arguments of a macro must be datatypes.

MyCoolMacro! (udim2 (500px))

Overloading

You can define multiple macros with the same name but with a different amount of parameters.

-- Padding A
@macro Padding (&all) {
    ::UIPadding {
        PaddingTop = &all;
        PaddingBottom = &all;
        PaddingLeft = &all;
        PaddingRight = &all;
    }
}

-- Padding B
@macro Padding (&top_bottom, &left_right) {
    ::UIPadding {
        PaddingTop = &top_bottom;
        PaddingBottom = &top_bottom;
        PaddingLeft = &left_right;
        PaddingRight = &left_right;
    }
}

-- Padding C
@macro Padding (&top, &left_right, &bottom) {
    ::UIPadding {
        PaddingTop = ⊤
        PaddingLeft = &left_right;
        PaddingRight = &left_right;
        PaddingBottom = ⊥
    }
}

-- Padding D
@macro Padding (&top, &right, &bottom, &left) {
    ::UIPadding {
        PaddingTop = ⊤
        PaddingRight = &right;
        PaddingBottom = ⊥
        PaddingLeft = &left;
    }
}

.Button {
    -- `Padding C` will be called
    -- as we have three parameters.
    Padding! (10px, 20px, 8px);
}

Built-In Macros

RSML has some macros built-in to speed up development: Padding (seen in the example above), CornerRadius, and Scale. An up to date list can be found here.