Payload routing

let orders = []fn price(items: list) -> num = items | map((i) => i.price ?? 0) | sumroute POST /orders { json: { type: "order" | "refund", customer.id: int as id, total: num } } {    let order = { id: len(orders) + 1, type: request.json.type, customer: id, total }    orders = orders | push(order)    reply 201 order}route POST /orders { json: { type: "quote", items: list } } = { quote: price(items) }route POST /orders = reply 422 { error: "expected type order, refund or quote" }route GET /orders ? { customer: int = null } =    customer == null        ? orders        : orders | filter((o) => o.customer == customer)// Middleware is just a function in a pipeline. `reply` stops the request.let admin = {    only: (req) =>        req.headers["x-api-key"] == env("ADMIN_KEY", "dev-key")            ? req            : reply 401 { error: "missing or wrong x-api-key" },}route DELETE /orders = request | admin.only | (_) => {    let n = len(orders)    orders = []    { deleted: n }}