jac-node-edge-patterns

Declare graph-persistent entities with `node` archetypes and connections with `edge` archetypes, optionally typed with endpoints like `edge Follows: Person --> Person`. Connect instances using `++>` for untyped edges or `+>:EdgeType(fields):+>` for typed edges with field values.

Nest a `[?...]` filter inside the reference, such as `[root -->[?:Person, age > 30]]` for node type and field predicates, or `[a ->:Follows:since > 2020:->]` for edge-attribute predicates. Filters compose per hop in multi-hop chains and predicates AND together.

The colon-assign form `+>:E:field=val:+>` parses but silently drops the assignment, leaving fields at defaults. Always pass field values through the constructor parentheses: `+>:E(field=val):+>`.

Edges declared without endpoint types give no type information to the checker, so attribute access only warns and typed function calls fail. Declare endpoints on the edge (`edge E: Src --> Tgt {}`) or nest `[?:NodeType]` at the read site.

The `del -->` operator works only on untyped edges. For typed edges, query the edge objects with `[edge a ->:E:-> b]` and delete each in a loop; deleting a node cascades to all of its edges.

`jac run` persists graph state in the `.jac/` directory, so each run adds new copies of nodes. Reset with `jac clean --all` or remove the `.jac/` directory before re-running.