wrap

lib/call.ts

@@ -9,6 +9,8 @@ function isPromise(p: unknown): boolean {
   if (!p) return false;
   return isFunc((p as PromiseLike<unknown>).then);
 }
+// iterator must implement both `.next` and `.throw`
+// built-in iterators are not considered iterators to `call()`
 function isIterator(it: unknown): boolean {
   if (!it) return false;
   return isFunc((it as Iterator<unknown>).next) &&
@@ -68,12 +70,18 @@ export function call<T>(callable: Callable<T>): Operation<T | Iterable<T>> {
   return action(function* (resolve, reject) {
     try {
       let op = typeof callable === "function" ? callable() : callable;
-      if (isIterable(op)) {
-        resolve(yield* op as Operation<T>);
+      if (isPromise(op)) {
+        resolve(yield* expect(op as Promise<T>));
       } else if (isIterator(op)) {
         resolve(yield* op as Operation<T>);
-      } else if (isPromise(op)) {
-        resolve(yield* expect(op as Promise<T>));
+      } else if (isIterable(op)) {
+        let iterable = op as Iterable<unknown>;
+        let iter = iterable[Symbol.iterator]();
+        if (isIterator(iter)) {
+          resolve(yield* op as Operation<T>);
+        } else {
+          resolve(op as T);
+        }
       } else {
         resolve(op as T);
       }

test/call.test.ts

@@ -62,7 +62,24 @@ describe("call", () => {
     await expect(run(() => call(() => 42))).resolves.toEqual(42);
   });
 
-  it.only("evaluates a vanilla function that returns an iterable", async () => {
+  it("evaluates a vanilla function that returns an iterable string", async () => {
     await expect(run(() => call(() => "123"))).resolves.toEqual("123");
   });
+
+  it("evaluates a vanilla function that returns an iterable array", async () => {
+    await expect(run(() => call(() => [1, 2, 3]))).resolves.toEqual([1, 2, 3]);
+  });
+
+  it("evaluates a vanilla function that returns an iterable map", async () => {
+    let map = new Map();
+    map.set("1", 1);
+    map.set("2", 2);
+    map.set("3", 3);
+    await expect(run(() => call(() => map))).resolves.toEqual(map);
+  });
+
+  it("evaluates a vanilla function that returns an iterable set", async () => {
+    let arr = new Set([1, 2, 3]);
+    await expect(run(() => call(() => arr))).resolves.toEqual(arr);
+  });
 });