What is 'foldIn' and 'foldOut' of Modifier??

# compose

[chanjungskim]

What is 'foldIn' and 'foldOut' of Modifier??

[Loney Chou]

It's like Iterable.fold but Modifier version. When you construct a Modifier chain using then or whatever its wrapper like Modifier.size, the element at the front is called outer, while at the back is inner. So foldIn iterates from the first to the last, the other one backwards.

[Loney Chou]

Modifier
    .size
    .padding
    .background
    .foldIn(Unit) { _, element ->
        println(element::class.simpleName)
    }

will print

SizeElement
PaddingElement
BackgroundElement

[chanjungskim]

When do you use foldIn and foldOut?

[Loney Chou]

Probably never. It's like something that is used for internal stuff.

[dewildte]

@chanjungskim https://en.wikipedia.org/wiki/Fold_(higher-order_function)