kw group

Query       = "from" Pattern "in" Expr { "where" Expr } [ "order" "by" Ord { "," Ord } ]
              [ "group" "by" Expr "into" Ident ] [ "skip" Expr ] [ "take" Expr ]
              [ "load" "(" IdentList ")" ] [ "select" Expr ] ;

@retain(ORDER_EVENTS_RETENTION)
topic OrderEvents: OrderEvent sharded by .userId

emit OrderEvents(e)                                       // publication
for await e in OrderEvents.subscribe(key: uid, from: .Latest) { … }
for await e in OrderEvents.subscribe(group: "indexer") { index(e) }

let top = from o in db.Order
  where o.userId == uid && o.total > MIN_TOTAL
  order by o.createdAt desc
  skip page * PAGE_SIZE
  take PAGE_SIZE
  load(items)

let names = from u in users where u.active select u.name   // in-memory List
let byRole = from u in users group by u.role into g select (g.key, g.count())