From 3f84d1e12fe78ea25645a7a46a169f0185a58fd0 Mon Sep 17 00:00:00 2001
From: Ben Styles <enquiries@leeds-ebooks.co.uk>
Date: Thu, 8 Feb 2018 11:46:53 +0000
Subject: [PATCH 1/2] Add orJustCall, with tests

---
 src/maybe.js      |  8 ++++++++
 src/maybe.js.flow |  2 ++
 src/maybe.test.js | 12 ++++++++++++
 3 files changed, 22 insertions(+)

diff --git a/src/maybe.js b/src/maybe.js
index c391cf7..5e5bb52 100644
--- a/src/maybe.js
+++ b/src/maybe.js
@@ -55,6 +55,10 @@ class Just<A> {
     return this.value
   }
 
+  orJustCall(): A {
+    return this.value
+  }
+
 }
 
 class Nothing {
@@ -93,6 +97,10 @@ class Nothing {
     return value
   }
 
+  orJustCall<B>(f: () => B): B {
+    return f()
+  }
+
 }
 
 function isNil<T>(value: ?T): boolean {
diff --git a/src/maybe.js.flow b/src/maybe.js.flow
index 332f766..25d8156 100644
--- a/src/maybe.js.flow
+++ b/src/maybe.js.flow
@@ -14,6 +14,7 @@ declare class Just<A> {
   map<B: AnyVal>(f: (_: A) => B): Maybe<B>;
   orElse<B>(m: Maybe<B>): Maybe<A>;
   orJust<B>(value: B): A;
+  orJustCall<B>(f: () => B): A;
 }
 
 declare class Nothing {
@@ -26,6 +27,7 @@ declare class Nothing {
   map<A, B: AnyVal>(f: (_: A) => B): Nothing;
   orElse<B>(m: Maybe<B>): Maybe<B>;
   orJust<B>(value: B): B;
+  orJustCall<B>(f: () => B): B;
 }
 
 declare export function just<T>(value: AnyVal): Just<T>;
diff --git a/src/maybe.test.js b/src/maybe.test.js
index bc41836..7332e57 100644
--- a/src/maybe.test.js
+++ b/src/maybe.test.js
@@ -44,6 +44,18 @@ test('orJust', () => {
   expect(y.orJust()).toBe('hello')
 })
 
+test('orJustCall', () => {
+  const x = maybe(null)
+  const orValue = x.orJustCall(() => 'hi')
+  expect(orValue).toBe('hi')
+  const y = maybe('hello')
+  expect(y.orJustCall()).toBe('hello')
+  expect(y.orJustCall(() => 'bye')).toBe('hello')
+  const fn = jest.fn(() => 'bye')
+  expect(y.orJustCall(fn)).toBe('hello')
+  expect(fn).not.toHaveBeenCalled()
+})
+
 test('map value', () => {
   const x = maybe('bob')
   const result = x.map(v => v.toUpperCase())

From 47ed9465dc2693e5bd7a7a668bec7967b3cc83ff Mon Sep 17 00:00:00 2001
From: Ben Styles <enquiries@leeds-ebooks.co.uk>
Date: Thu, 8 Feb 2018 12:00:38 +0000
Subject: [PATCH 2/2] removed failing (and unnecessary) expectation

---
 src/maybe.test.js | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/maybe.test.js b/src/maybe.test.js
index 7332e57..998080e 100644
--- a/src/maybe.test.js
+++ b/src/maybe.test.js
@@ -49,7 +49,6 @@ test('orJustCall', () => {
   const orValue = x.orJustCall(() => 'hi')
   expect(orValue).toBe('hi')
   const y = maybe('hello')
-  expect(y.orJustCall()).toBe('hello')
   expect(y.orJustCall(() => 'bye')).toBe('hello')
   const fn = jest.fn(() => 'bye')
   expect(y.orJustCall(fn)).toBe('hello')