Hey, y'all! We're slowly transitioning into using ...

# arrow

[sindrenm]

Hey, y'all! We're slowly transitioning into using Optics (with generated extensions) for a nicer way of dealing with manipulating deeply nested immutable data classes, and I'm loving what it does for me so far. However, I'm getting a little lost when dealing with collections, and I was hoping someone here could guide me in the right direction.

I've got something like this:

@optics
data class Container(val items: List<Item>) { companion object }

@optics
data class Item(val value: String) { companion object }

I would like to, given a Container, replace all of the items inside it that matches a condition with another Item. Something like:

fun main() {
    val container = Container(listOf(Item("foo"), Item("bar"), Item("baz")))
    val newContainer: Container = TODO("""Use optics to convert all Item("bar") with Item("replaced")""")
    assert(newContainer.items[1].value == "replaced")
}

I've been trying to go down the route of <http://Container.items.at|Container.items.at>(...) route, but I can't really seem to figure out the At APIs. Something like

<http://Container.items.at|Container.items.at> { it.id == "bar" }.modify { Item("replaced") }

would make sense to me, but the API's are clearly a little different than that.