feat: add the zip function to the Optional type

Sources/SwiftExtended/Optional.swift

@@ -99,6 +99,30 @@ public extension Optional {
     }
 }
 
+public extension Optional {
+    /// Combines (zips) the given value with the existing one - if any - to produce a tuple.
+    ///
+    /// The tuple is only produced when both optional values contain a value; otherwise, it returns `Optional.none`.
+    ///
+    /// ```swift
+    /// let credentials: Credentials? = usernameTextField
+    ///     .text
+    ///     .zip(with: passwordTextField.text)
+    ///     .map { username, password in
+    ///         Credentials(username: username, password: password)
+    ///     }
+    /// ```
+    ///
+    /// - Parameter other: The value to combine.
+    /// - Returns: A tuple containing the zipped values.
+    func zip<Other>(with other: Other?) -> (Wrapped, Other)? {
+        guard let self, let other else {
+            return nil
+        }
+        return (self, other)
+    }
+}
+
 public extension Optional where Wrapped: Equatable {
     /// Checks if the value is wrapped within the `Optional` type.
     /// - Parameter value: The value to search for.

Tests/SwiftExtendedTests/OptionalTests.swift

@@ -143,4 +143,33 @@ final class OptionalTests: XCTestCase {
                 .contains(letterA)
         )
     }
+
+    func testZip() throws {
+        // given
+        let leftHandSideValue = 1
+        let rightHandSideValue = "A"
+
+        // when
+        let unzippedPair = try XCTUnwrap(
+            Optional
+                .some(leftHandSideValue)
+                .zip(with: Optional.some(rightHandSideValue))
+        )
+
+        // then
+        XCTAssertEqual(leftHandSideValue, unzippedPair.0)
+        XCTAssertEqual(rightHandSideValue, unzippedPair.1)
+
+        // and when
+        let nilDueToLeftHandSide = Optional<Int>
+            .none
+            .zip(with: Optional.some(rightHandSideValue))
+        let nilDueToRightHandSide = Optional
+            .some(leftHandSideValue)
+            .zip(with: Optional<String>.none)
+
+        // then
+        XCTAssertNil(nilDueToLeftHandSide)
+        XCTAssertNil(nilDueToRightHandSide)
+    }
 }