Add an example of reactive recursive tree component

[godstail]

Something like:

#[derive(Debug, Clone, PartialEq, sycamore::Prop)]
pub struct MyNode<'a> {
    text: &'a Signal<String>,
    leafs: &'a Signal<Vec<MyNode<'a>>>,
}

#[component]
pub fn MyNodeComp<'a, G: Html>(
    cx: Scope<'a>, 
    node: MyNode<'a>) -> View<G> 
{
    view! { cx,
        div {
            div { ( node.text.get() ) }
            input(bind:value = node.text)
            Indexed {
                iterable: node.leafs,
                view: |cx, leaf| view! { cx, MyNodeComp(leaf) }
            }
        }
    }
}

At the time of 0.8.0-beta.7 this doesn't compile due to lifetime inference error.

[godstail]

RcSignal with create_ref() work:

#[derive(Debug, Clone, PartialEq, sycamore::Prop)]
pub struct MyNode {
    text: RcSignal<String>,
    leafs: RcSignal<Vec<MyNode>>,
}

#[component]
pub fn MyNodeComp<G: Html>(
    cx: Scope, 
    node: MyNode
) -> View<G> 
{
    let text_clone_ref = create_ref(cx, node.text.clone());
    let leafs_ref = create_ref(cx, node.leafs);
    
    view! { cx,
        div {
            div { ( node.text.get() ) }
            input(bind:value = text_clone_ref)
            Indexed {
                iterable: leafs_ref,
                view: |cx, leaf| view! { cx, MyNodeComp(leaf) }
            }
        }
    }
}

[godstail]

With Rust 1.63 first component now compiles with a trick of additional lifetime 'b: 'a.

#[derive(Debug, Clone, PartialEq, sycamore::Prop)]
pub struct MyNode<'a> {
    text: &'a Signal<String>,
    leafs: &'a Signal<Vec<MyNode<'a>>>,
}

#[component]
pub fn MyNodeComp<'a, 'b: 'a, G: Html>(
    cx: Scope<'a>, 
    node: MyNode<'b>) -> View<G> 
{
    view! { cx,
        div {
            div { ( node.text.get() ) }
            input(bind:value = node.text)
            Indexed {
                iterable: node.leafs,
                view: |cx, leaf| view! { cx, MyNodeComp(leaf) }
            }
        }
    }
}