2 Ids

Nodes, pins, edges and anchors carry your own id types, and a pin can carry a payload. Those five types are named once, on a marker implementing Ids; Indexed (usize ids, no edge id, no payload) is the default and what node_graph builds. Any type that is Clone + Eq + Hash + Debug + Send + Sync + 'static is an id, so a newtype, an enum or a uuid::Uuid needs no impl.

use iced_nodegraph::{Ids, NodeGraph, PinRef, node};
use iced::{Element, Point};
use iced::widget::text;

#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
struct AppIds;

impl Ids for AppIds {
    type NodeId = u64;
    type PinId = &'static str;
    type EdgeId = u64;
    type AnchorId = usize;
    type Payload = ();
}

#[derive(Debug, Clone)]
enum Message {
    Connected(PinRef<AppIds>, PinRef<AppIds>),
}

fn view() -> Element<'static, Message> {
    NodeGraph::<AppIds, _, _, _>::new()
        .on_connect(Message::Connected)
        .push_node(node(7, Point::ORIGIN, text("seven")))
        .into()
}

The marker is the one type the compiler cannot infer, so it is named on the graph and in the messages that carry a PinRef; every builder and callback infers it from there.