chore(internal): Define TotalMap<K, V> and TotalMapFrom<Map<K, V>> types

Ref microsoft/TypeScript#9619

packages/internal/src/storage-test-utils.js

@@ -9,25 +9,12 @@ import { bindAllMethods } from './method-tools.js';
 import { eventLoopIteration } from './testing-utils.js';
 
 /**
+ * @import {TotalMap} from './types.js';
  * @import {Marshaller, StorageEntry, StorageMessage, StorageNode} from './lib-chainStorage.js';
  */
 
 const trace = makeTracer('StorTU', false);
 
-/**
- * A map corresponding with a total function such that `get(key)` is assumed to
- * always succeed.
- *
- * @template K, V
- * @typedef {{ [k in Exclude<keyof Map<K, V>, 'get'>]: Map<K, V>[k] } & {
- *   get: (key: K) => V;
- * }} TotalMap
- */
-/**
- * @template T
- * @typedef {T extends Map<infer K, infer V> ? TotalMap<K, V> : never} TotalMapFrom
- */
-
 /**
  * A convertSlotToVal function that produces basic Remotables. Assumes that all
  * slots are Remotables (i.e. none are Promises).

packages/internal/src/types.d.ts

@@ -3,6 +3,18 @@ import type { ERef, RemotableBrand } from '@endo/eventual-send';
 import type { Primitive } from '@endo/pass-style';
 import type { Callable } from './utils.js';
 
+/**
+ * A map corresponding with a total function such that `get(key)` is assumed to
+ * always succeed.
+ */
+export type TotalMap<K, V> = {
+  [k in Exclude<keyof Map<K, V>, 'get'>]: Map<K, V>[k];
+} & {
+  get: (key: K) => V;
+};
+export type TotalMapFrom<M> =
+  M extends Map<infer K, infer V> ? TotalMap<K, V> : never;
+
 export declare class Callback<I extends (...args: unknown[]) => any> {
   private iface: I;