// activate.el — The `activate` construct: spreading activation over the type graph.
//
// The `activate` keyword is the most novel feature of the Engram language.
// Instead of querying a database with SQL or a key lookup, you query the
// *type graph* using a natural language description. The result is
// statically typed — the compiler knows you get [User] back, not Any.
//
// How it works:
//
// 1. At compile time, the type checker verifies that `User` is a registered
//    type with a corresponding Engram node mapping.
//
// 2. At runtime, the Engram runtime performs spreading activation over
//    the knowledge graph, starting from the User node, propagating to
//    semantically related nodes with co-activation energy proportional
//    to edge weights and node salience.
//
// 3. The query string "customer who purchased recently" is embedded
//    and used as a semantic filter: only nodes whose embeddings are
//    within cosine-similarity threshold of the query embedding are returned.
//
// 4. The result is type-safe: [User]. You don't get back Any or a JSON blob.
//    The type checker enforces this at compile time.

type User {
    id: Uuid
    name: String
    email: String
}

type Order {
    id: Uuid
    user_id: Uuid
    amount: Float
    status: String
}

// Query: find all users who are semantically related to "customer who purchased recently"
// The result type is [User] — an array of User nodes from the knowledge graph.
let recent_buyers: [User] = activate User where "customer who purchased recently"

// You can also activate on other types:
let pending_orders: [Order] = activate Order where "order awaiting fulfillment"

// Spreading activation respects the type graph edges.
// If User and Customer share an Engram node type (e.g. "Entity"),
// they are semantically compatible — the type checker allows
// treating one as the other when they map to the same Engram node class.

fn process_buyers(users: [User]) -> String {
    return "processing users"
}

let result: String = process_buyers(recent_buyers)