feat(extract): add extracting contained value from unwrap

operators/extract.ts

@@ -0,0 +1,31 @@
+// 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 contained `Some` value.
+ *
+ * @example
+ * ```ts
+ * import { Some } from "https://deno.land/x/optio/spec.ts";
+ * import { unwrap } from "https://deno.land/x/optio/operators/extract.ts";
+ * import { assertEquals } from "https://deno.land/std/testing/asserts.ts";
+ *
+ * assertEquals(unwrap(Some.of(0)), 0);
+ * ```
+ * @throws {Error} if the {@link option} is `None`.
+ * @example
+ * ```ts
+ * import { None } from "https://deno.land/x/optio/spec.ts";
+ * import { unwrap } from "https://deno.land/x/optio/operators/extract.ts";
+ * import { assertThrows } from "https://deno.land/std/testing/asserts.ts";
+ *
+ * assertThrows(() => unwrap(None));
+ * ```
+ */
+export function unwrap<T>(option: Option<T>): T {
+  if (isSome(option)) return option.get;
+
+  throw new Error("option is None");
+}

operators/extract_test.ts

@@ -0,0 +1,16 @@
+// Copyright © 2023 Tomoki Miyauchi. All rights reserved. MIT license.
+// This module is browser compatible.
+
+import { unwrap } from "./extract.ts";
+import { None, Some } from "../spec.ts";
+import { assertEquals, assertThrows, describe, it } from "../_dev_deps.ts";
+
+describe("unwrap", () => {
+  it("should return some value", () => {
+    assertEquals(unwrap(Some.of(0)), 0);
+  });
+
+  it("should throw error if None", () => {
+    assertThrows(() => unwrap(None), Error, "option is None");
+  });
+});