feat(Maybe): add tryLast, bump to beta.4

package.json

@@ -1,7 +1,7 @@
 {
   "name": "typescript-functional-extensions",
   "description": "A TypeScript implementation of https://github.com/vkhorikov/CSharpFunctionalExtensions",
-  "version": "1.0.0-beta.3",
+  "version": "1.0.0-beta.4",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",
   "type": "module",

src/maybe.ts

@@ -75,6 +75,42 @@ export class Maybe<TValue> {
     }
   }
 
+  /**
+   * Returns a Maybe containing the last value of the array,
+   * and a Maybe.none if the array is empty
+   * @param values
+   */
+  static tryLast<TValue>(values: TValue[]): Maybe<TValue>;
+  /**
+   * Returns a Maybe containing the value of the last element
+   * of the array matching the condition of the predicate, and
+   * a Maybe.none if there are no matches
+   * @param values
+   * @param predicate
+   */
+  static tryLast<TValue>(
+    values: Some<TValue>[],
+    predicate: PredicateOfT<Some<TValue>>
+  ): Maybe<TValue>;
+  static tryLast<TValue>(
+    values: Some<TValue>[],
+    predicate?: PredicateOfT<Some<TValue>>
+  ): Maybe<TValue> {
+    if (isFunction(predicate)) {
+      for (let index = values.length - 1; index >= 0; index--) {
+        const value = values[index];
+
+        if (predicate(value)) {
+          return new Maybe(value);
+        }
+      }
+
+      return Maybe.none();
+    } else {
+      return new Maybe(values[values.length - 1]);
+    }
+  }
+
   /**
    * Returns only the Maybe instances of the array that have
    * values

test/maybe/tryLast.spec.ts

@@ -0,0 +1,36 @@
+import { Maybe } from '@/src/maybe';
+describe('Maybe', () => {
+  describe('tryLast', () => {
+    test('creates a Maybe with a value when the array has a value', () => {
+      const items = [1, 2, 3];
+
+      const sut = Maybe.tryLast(items);
+
+      expect(sut).toHaveValue(items[2]);
+    });
+
+    test('creates a Maybe with no value when the array is empty', () => {
+      const items: number[] = [];
+
+      const sut = Maybe.tryLast(items);
+
+      expect(sut).toHaveNoValue();
+    });
+
+    test('creates a Maybe with the last value which matches the predicate', () => {
+      const items = [1, 2, 3, 4];
+
+      const sut = Maybe.tryLast(items, (i) => i > 2);
+
+      expect(sut).toHaveValue(4);
+    });
+
+    test('creates a Maybe with no value when the predicate has no matches', () => {
+      const items = [1, 2, 3, 4];
+
+      const sut = Maybe.tryLast(items, (i) => i > 10);
+
+      expect(sut).toHaveNoValue();
+    });
+  });
+});