From ea38efb238081c4596567785391201ae07d55989 Mon Sep 17 00:00:00 2001
From: David Retzlaff <david.retzlaff@bluehands.de>
Date: Fri, 31 Jan 2025 09:17:39 +0100
Subject: [PATCH] Add or else methods to option closes #31

---
 Source/FunicularSwitch/Option.cs              | 37 +++++++++++++++++--
 .../Tests/FunicularSwitch.Test/OptionSpecs.cs | 17 +++++++++
 2 files changed, 51 insertions(+), 3 deletions(-)

diff --git a/Source/FunicularSwitch/Option.cs b/Source/FunicularSwitch/Option.cs
index 3773294..9a42308 100644
--- a/Source/FunicularSwitch/Option.cs
+++ b/Source/FunicularSwitch/Option.cs
@@ -59,6 +59,11 @@ public Task<Option<T1>> Map<T1>(Func<T, Task<T1>> map) => Match(
         public Option<T1> Bind<T1>(Func<T, Option<T1>> map) => Match(map, Option<T1>.None);
 
         public Task<Option<T1>> Bind<T1>(Func<T, Task<Option<T1>>> bind) => Match(bind, () => Option<T1>.None);
+        
+        public Option<T> OrElse(Option<T> other) => _isSome ? this : other;
+        public Option<T> OrElse(Func<Option<T>> other) => _isSome ? this : other();
+        public Task<Option<T>> OrElse(Task<Option<T>> other) => OrElse(() => other);
+        public async Task<Option<T>> OrElse(Func<Task<Option<T>>> other) => _isSome ? this : await other().ConfigureAwait(false);
 
         public void Match(Action<T> some, Action? none = null)
         {
@@ -90,6 +95,8 @@ public async Task<TResult> Match<TResult>(Func<T, Task<TResult>> some, Func<Task
 
             return await none().ConfigureAwait(false);
         }
+        
+        
 
         public async Task<TResult> Match<TResult>(Func<T, Task<TResult>> some, Func<TResult> none)
         {
@@ -202,15 +209,39 @@ public static async Task<Option<TOut>> Bind<T, TOut>(this Task<Option<T>> bind,
             var result = await bind.ConfigureAwait(false);
             return await result.Bind(convert).ConfigureAwait(false);
         }
+        
+        public static async Task<Option<T>> OrElse<T>(this Task<Option<T>> option, Option<T> other)
+        {
+            var result = await option.ConfigureAwait(false);
+            return result.OrElse(other);
+        }
+        
+        public static async Task<Option<T>> OrElse<T>(this Task<Option<T>> option, Func<Option<T>> other)
+        {
+            var result = await option.ConfigureAwait(false);
+            return result.OrElse(other);
+        }
+        
+        public static async Task<Option<T>> OrElse<T>(this Task<Option<T>> option, Task<Option<T>> other)
+        {
+            var result = await option.ConfigureAwait(false);
+            return await result.OrElse(other).ConfigureAwait(false);
+        }
+        
+        public static async Task<Option<T>> OrElse<T>(this Task<Option<T>> option, Func<Task<Option<T>>> other)
+        {
+            var result = await option.ConfigureAwait(false);
+            return await result.OrElse(other).ConfigureAwait(false);
+        }
 
         public static IEnumerable<TOut> Choose<T, TOut>(this IEnumerable<T> items, Func<T, Option<TOut>> choose) =>
-            items.SelectMany(i => choose(i));
+            items.SelectMany(i => choose(i));        
 
         public static Option<T> ToOption<T>(this Result<T> result) => result.ToOption(logError: null);
 
         public static Option<T> ToOption<T>(this Result<T> result, Action<string>? logError) =>
             result.Match(
-                ok => Option.Some(ok),
+                Option.Some,
                 error =>
                 {
                     logError?.Invoke(error);
@@ -218,7 +249,7 @@ public static Option<T> ToOption<T>(this Result<T> result, Action<string>? logEr
                 });
 
         public static Result<T> ToResult<T>(this Option<T> option, Func<string> errorIfNone) =>
-            option.Match(s => Result.Ok(s), () => Result.Error<T>(errorIfNone()));
+            option.Match(Result.Ok, () => Result.Error<T>(errorIfNone()));
 
         public static Option<string> NoneIfEmpty(this string? text)
             => text.ToOption(x => !string.IsNullOrEmpty(x));
diff --git a/Source/Tests/FunicularSwitch.Test/OptionSpecs.cs b/Source/Tests/FunicularSwitch.Test/OptionSpecs.cs
index e752569..ea16c0d 100644
--- a/Source/Tests/FunicularSwitch.Test/OptionSpecs.cs
+++ b/Source/Tests/FunicularSwitch.Test/OptionSpecs.cs
@@ -828,6 +828,23 @@ public void NoneIfEmpty_Text_Some()
         string? target = "Hi";
         var result = target.NoneIfEmpty();
         result.Should().BeSome().Which.Should().Be("Hi");
+    }
+
+    [TestMethod]
+    public async Task OrElse()
+    {
+        var none = None<int>();
+        none.OrElse(Option<int>.None).Should().BeNone();
+        ShouldBeSome42(none.OrElse(42));
+
+        var some = Some(42);
+        ShouldBeSome42(some.OrElse(Option<int>.None));
+        ShouldBeSome42(some.OrElse(2));
+
+        ShouldBeSome42(await none.OrElse(() => Task.FromResult(Some(42))));
+        return;
+
+        void ShouldBeSome42(Option<int> option) => option.Should().BeSome().Which.Should().Be(42);
     }
 
     class MyClass;