From ad5e392c42d02f7b33c882aa771949f891cd4dda Mon Sep 17 00:00:00 2001
From: Paolo Roth <iamoctod@gmail.com>
Date: Tue, 16 Jul 2019 14:19:26 +0200
Subject: [PATCH] feat: adds flattern

---
 README.md                    |  9 +++++++++
 src/Option.ts                | 18 ++++++++++++++++++
 src/__tests__/Option.spec.ts |  4 ++++
 3 files changed, 31 insertions(+)

diff --git a/README.md b/README.md
index d375adc..ff7fec5 100644
--- a/README.md
+++ b/README.md
@@ -14,6 +14,7 @@ Heavily inspired by rust [std::option](https://doc.rust-lang.org/std/option/inde
       - [andThen](#andThen)
       - [expect](#expect)
       - [filter](#filter)
+      - [flattern](#flattern)
       - [isNone](#isNone)
       - [isSome](#isSome)
       - [map](#map)
@@ -123,6 +124,14 @@ Option(1).filter(a => a > 0).isSome() // true
 Option(1).filter(a => a > 10).isSome() // false
 ```
 
+#### flattern
+
+Converts from `Option<Option<T>>` to `Option<T>`
+
+```ts
+Option(Some(100)).flattern() // Some(100)
+```
+
 #### isNone
 
 Returns if has not a value
diff --git a/src/Option.ts b/src/Option.ts
index 3a4314f..36a99de 100644
--- a/src/Option.ts
+++ b/src/Option.ts
@@ -89,6 +89,24 @@ class OptionLike<T> {
     return predicateresult ? this : (None() as any);
   }
 
+  /**
+   * Converts from `Option<Option<T>>` to `Option<T>`
+   *
+   * ```ts
+   * Option(Some(100)).flattern() // Some(100)
+   * ```
+   *
+   * @returns {OptionLike<T>}
+   * @memberof OptionLike
+   */
+  public flattern(): OptionLike<T> {
+    if (this.value instanceof OptionLike) {
+      return this.value;
+    }
+
+    return this;
+  }
+
   /**
    * Returns if has not a value
    *
diff --git a/src/__tests__/Option.spec.ts b/src/__tests__/Option.spec.ts
index 6d59a09..29f1997 100644
--- a/src/__tests__/Option.spec.ts
+++ b/src/__tests__/Option.spec.ts
@@ -118,4 +118,8 @@ describe(`Option`, () => {
     expect(Some(100).transpose()).toStrictEqual(Ok(Some(100)));
     expect(None().transpose()).toStrictEqual(Ok(None()));
   });
+
+  it("Converts from `Option<Option<T>>` to `Option<T>`", () => {
+    expect(Option(Some(100)).flattern()).toStrictEqual(Some(100));
+  });
 });