Change iter methods to the JS-idiomatic [Symbol.iterator]

Author: sck451

src/Option/None.ts

@@ -55,9 +55,7 @@ export class None<T = never> extends OptionBase<T> {
     return err(error);
   }
 
-  iter(): IteratorObject<T, unknown, unknown> {
-    return Iterator.from([]);
-  }
+  *[Symbol.iterator](): Iterator<T> {}
 
   and<U>(_optionB: Option<U>): None<never> {
     return none();

src/Option/OptionBase.ts

@@ -97,7 +97,7 @@ export abstract class OptionBase<T> {
    * Return an iterator over the {@link Some} value.
    * @returns A JavaScript iterator over 0 or 1 elements.
    */
-  abstract iter(): IteratorObject<T, unknown, unknown>;
+  abstract [Symbol.iterator](): Iterator<T>;
 
   /**
    * Return `optionB` if {@link Some}, otherwise `None`.

src/Option/Some.ts

@@ -59,8 +59,8 @@ export class Some<T> implements OptionBase<T> {
     return ok(this.value);
   }
 
-  iter(): IteratorObject<T, unknown, unknown> {
-    return Iterator.from([this.value]);
+  *[Symbol.iterator](): Iterator<T> {
+    yield this.value;
   }
 
   and<U>(optionB: Option<U>): Option<U> {

src/Result/Err.ts

@@ -60,9 +60,7 @@ export class Err<T = never, E = unknown> extends ResultBase<T, E> {
     return err(this.error);
   }
 
-  iter(): IteratorObject<T, unknown, unknown> {
-    return Iterator.from([] as T[]);
-  }
+  *[Symbol.iterator](): Iterator<T> {}
 
   unwrap(message: string = `Expected ok() but got ${this}`): never {
     throw new Error(message);

src/Result/Ok.ts

@@ -60,8 +60,8 @@ export class Ok<T, E = never> extends ResultBase<T, E> {
     return this;
   }
 
-  iter(): IteratorObject<T, unknown, unknown> {
-    return Iterator.from([this.value]);
+  *[Symbol.iterator](): Iterator<T> {
+    yield this.value;
   }
 
   unwrap(_message: string = `Expected ok() but got ${this}`): T {

src/Result/ResultBase.ts

@@ -92,7 +92,7 @@ export abstract class ResultBase<T, E = unknown> {
    * Get an iterator over the `Ok` value.
    * @returns An iterator yielding the `Ok` value or nothing if `Err`.
    */
-  abstract iter(): IteratorObject<T, unknown, unknown>;
+  abstract [Symbol.iterator](): Iterator<T>;
 
   /**
    * Unwrap the `Ok` value, or throw an error if `Err`.

tests/option_none_test.ts

@@ -73,8 +73,8 @@ Deno.test("none().okOr(n) returns err(n)", () => {
   expect(result.unwrapErr()).toBe("problem");
 });
 
-Deno.test("none().iter() returns an empty iterator", () => {
-  const collected = [...none().iter()];
+Deno.test("iterating over none().iter() yields nothing", () => {
+  const collected = [...none()];
   expect(collected.length).toBe(0);
 });
 

tests/option_some_test.ts

@@ -76,8 +76,8 @@ Deno.test("some(n).okOr() returns ok(n)", () => {
   expect(result.unwrap()).toBe(42);
 });
 
-Deno.test("some(n).iter() returns an iterator over [n]", () => {
-  const collected = [...some(42).iter()];
+Deno.test("iterating over some(n).iter() yields precisely n", () => {
+  const collected = [...some(42)];
   expect(collected.length).toBe(1);
   expect(collected[0]).toBe(42);
 });

tests/result_err_test.ts

@@ -83,15 +83,15 @@ Deno.test("ok.inspectErr() calls its callback", () => {
   expect(called).toBe(true);
 });
 
-// Deno.test({
-//   name: "ok(n).iter() gives an iterator containing nothing",
-//   fn: () => {
-//     const result = err("problem").iter();
-
-//     const collected = [...result];
-//     expect(collected.length).toBe(0);
-//   },
-// });
+Deno.test({
+  name: "iterating over err(e) yields nothing",
+  fn: () => {
+    const result = err("problem");
+
+    const collected = [...result];
+    expect(collected.length).toBe(0);
+  },
+});
 
 Deno.test("err().unwrap() throws", () => {
   expect(() => err("problem").unwrap()).toThrow();

tests/result_ok_test.ts

@@ -82,11 +82,11 @@ Deno.test("ok.inspectErr() does not call its callback", () => {
   expect(called).toBe(false);
 });
 
-// Deno.test("ok(n).iter() gives an iterator containing precisely n", () => {
-//   const collected = [...ok(42).iter()];
-//   expect(collected.length).toBe(1);
-//   expect(collected[0]).toBe(42);
-// });
+Deno.test("iterating over ok(n) yields precisely n", () => {
+  const collected = [...ok(42)];
+  expect(collected.length).toBe(1);
+  expect(collected[0]).toBe(42);
+});
 
 Deno.test("ok(n).unwrap() returns n", () => {
   expect(ok(42).unwrap()).toBe(42);