feat: Support using (#886)

src/index.js

@@ -25,6 +25,9 @@ import { Errors, PostgresError } from './errors.js'
 import Subscribe from './subscribe.js'
 import largeObject from './large.js'
 
+// Polyfill for `Symbol.dispose`. We don't need asyncDispose as sql.release() is not async.
+Symbol.dispose ??= Symbol("Symbol.dispose")
+
 Object.assign(Postgres, {
   PostgresError,
   toPascal,
@@ -221,6 +224,7 @@ function Postgres(a, b) {
       c.reserved = null
       onopen(c)
     }
+    sql[Symbol.dispose] = sql.release;
 
     return sql
 

types/index.d.ts

@@ -20,6 +20,15 @@ declare function postgres<T extends Record<string, postgres.PostgresType> = {}>(
   parse: (raw: any) => infer R
 } ? R : never }>
 
+// Disposable type for `using sql = ...` syntax.
+// If typescript doesn't know about `Symbol.dispose`, fallback to an empty interface.
+type Disposable = typeof Symbol extends {
+  dispose: symbol;
+} //@ts-ignore
+  ? {[Symbol.dispose]: () => void;
+  }
+  : {};
+
 /**
  * Connection options of Postgres.
  */
@@ -722,7 +731,7 @@ declare namespace postgres {
     prepare<T>(name: string): Promise<UnwrapPromiseArray<T>>;
   }
 
-  interface ReservedSql<TTypes extends Record<string, unknown> = {}> extends Sql<TTypes> {
+  interface ReservedSql<TTypes extends Record<string, unknown> = {}> extends Sql<TTypes>, Disposable {
     release(): void;
   }
 }