feat: add toString

Add toString(separator) method for Sequence

src/Sequence.ts

@@ -326,6 +326,12 @@ export class SequenceImpl<TItem> implements Iterable<TItem>, Sequence<TItem> {
     return new Set(this._iterable);
   }
 
+  toString(separator: string = ","): string {
+    return Array.isArray(this._iterable)
+      ? this._iterable.join(separator)
+      : copyIntoAnArray(this._iterable).join(separator);
+  }
+
   private _sequenceFromGenerator<TResult = TItem>(
     factoryFn: Function,
     restArgs?: any[]

src/types.ts

@@ -610,6 +610,21 @@ export interface Sequence<TItem> extends Iterable<TItem> {
    * ```
    */
   toSet(): Set<TItem>;
+  /**
+   * Converts the sequence to a string using the given separator
+   *
+   * @param separator A string used to separate one element of a sequence from the next in the resulting String. If omitted, the elements are separated with a comma.
+   *
+   * @example
+   * ```typescript
+   * // Returns a string "1,2,3"
+   * from([1, 2, 3]).toString();
+   *
+   * // Returns a string "1 - 2 - 3"
+   * from([1, 2, 3]).toString(" - ");
+   * ```
+   */
+  toString(separator?: string): string;
 }
 
 /**

test/fromfrom.test.ts

@@ -1347,4 +1347,29 @@ describe("fromfrom", () => {
       expect(from([1, 2]).toSet()).toEqual(new Set([1, 2]));
     });
   });
+
+  describe("toString", () => {
+    it("returns a string", () => {
+      expect(from([1, 2]).toString(",")).toEqual("1,2");
+    });
+
+    it("uses comma as a default separator", () => {
+      expect(from([1, 2]).toString()).toEqual("1,2");
+    });
+
+    it("can be given a custom separator", () => {
+      expect(from([1, 2]).toString("_")).toEqual("1_2");
+    });
+
+    it("works with generator input", () => {
+      function* generate() {
+        let i = 1;
+        while (i < 3) {
+          yield i;
+          i++;
+        }
+      }
+      expect(from(generate()).toString("_")).toEqual("1_2");
+    });
+  });
 });