feat(logical): add or operator for option

operators/logical.ts

@@ -0,0 +1,25 @@
+// Copyright © 2023 Tomoki Miyauchi. All rights reserved. MIT license.
+// This module is browser compatible.
+
+import { isSome } from "./query.ts";
+import { type Option } from "../spec.ts";
+
+/** Returns the {@link option} if it contains a value, otherwise returns {@link obtb}.
+ *
+ * @example
+ * ```ts
+ * import { None, or, Some } from "https://deno.land/x/optio/mod.ts";
+ * import { assertEquals } from "https://deno.land/std/testing/asserts.ts";
+ *
+ * const x = Some.of(2);
+ * assertEquals(or(x, None), Some.of(2));
+ *
+ * const y = None;
+ * assertEquals(or(y, Some.of(100)), Some.of(100));
+ * ```
+ */
+export function or<T>(option: Option<T>, obtb: Option<T>): Option<T> {
+  if (isSome(option)) return option;
+
+  return obtb;
+}

operators/logical_test.ts

@@ -0,0 +1,20 @@
+// Copyright © 2023 Tomoki Miyauchi. All rights reserved. MIT license.
+// This module is browser compatible.
+
+import { or } from "./logical.ts";
+import { None, Some } from "../spec.ts";
+import { assert, describe, it } from "../_dev_deps.ts";
+
+describe("or", () => {
+  it("should return option if it is Some", () => {
+    const option = Some.of(0);
+    assert(or(option, Some.of(0)) === option);
+    assert(or(option, None) === option);
+  });
+
+  it("should return optb if it is None", () => {
+    const optb = Some.of(0);
+    assert(or(None, optb) === optb);
+    assert(or(None, None) === None);
+  });
+});