From 94ad6e57d718e9b2659f10c752cf18a4fe12b700 Mon Sep 17 00:00:00 2001
From: Robin Ehlert <post@rehlert.de>
Date: Wed, 23 Jul 2025 08:43:59 +0200
Subject: [PATCH] Add initial project structure with Result type and extension
 methods

---
 .gitignore                                    |   6 +
 Rehlert.RoP.sln                               |  16 +++
 Rehlert.RoP/Extensions/FallbackExtensions.cs  |  28 +++++
 Rehlert.RoP/Extensions/OnErrorExtensions.cs   |  55 ++++++++
 Rehlert.RoP/Extensions/OnSuccessExtensions.cs | 118 ++++++++++++++++++
 Rehlert.RoP/Rehlert.RoP.csproj                |  13 ++
 Rehlert.RoP/Result.cs                         |  13 ++
 7 files changed, 249 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 Rehlert.RoP.sln
 create mode 100644 Rehlert.RoP/Extensions/FallbackExtensions.cs
 create mode 100644 Rehlert.RoP/Extensions/OnErrorExtensions.cs
 create mode 100644 Rehlert.RoP/Extensions/OnSuccessExtensions.cs
 create mode 100644 Rehlert.RoP/Rehlert.RoP.csproj
 create mode 100644 Rehlert.RoP/Result.cs

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..da23fc0
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,6 @@
+bin/
+obj/
+.idea/
+/packages/
+riderModule.iml
+/_ReSharper.Caches/
diff --git a/Rehlert.RoP.sln b/Rehlert.RoP.sln
new file mode 100644
index 0000000..983aa99
--- /dev/null
+++ b/Rehlert.RoP.sln
@@ -0,0 +1,16 @@
+
+Microsoft Visual Studio Solution File, Format Version 12.00
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Rehlert.RoP", "Rehlert.RoP\Rehlert.RoP.csproj", "{C043B9E4-712D-4710-972E-1D89A31A9E2D}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{C043B9E4-712D-4710-972E-1D89A31A9E2D}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{C043B9E4-712D-4710-972E-1D89A31A9E2D}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{C043B9E4-712D-4710-972E-1D89A31A9E2D}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{C043B9E4-712D-4710-972E-1D89A31A9E2D}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+EndGlobal
diff --git a/Rehlert.RoP/Extensions/FallbackExtensions.cs b/Rehlert.RoP/Extensions/FallbackExtensions.cs
new file mode 100644
index 0000000..a3ff0ae
--- /dev/null
+++ b/Rehlert.RoP/Extensions/FallbackExtensions.cs
@@ -0,0 +1,28 @@
+namespace Rehlert.RoP.Extensions;
+
+public static class FallbackExtensions
+{
+    public static TIn FallbackWith<TIn, TErr>(this Result<TIn, TErr> value, TIn defaultValue)
+    {
+        var result = value.Match(
+            ok => ok.Value,
+            _ => defaultValue
+        );
+
+        return result;
+    }
+
+    public static async Task<TIn> FallbackWith<TIn, TErr>(
+        this Task<Result<TIn, TErr>> value,
+        TIn defaultValue
+    )
+    {
+        var valRes = await value;
+        var result = valRes.Match(
+            ok => ok.Value,
+            _ => defaultValue
+        );
+
+        return result;
+    }
+}
\ No newline at end of file
diff --git a/Rehlert.RoP/Extensions/OnErrorExtensions.cs b/Rehlert.RoP/Extensions/OnErrorExtensions.cs
new file mode 100644
index 0000000..e111bc1
--- /dev/null
+++ b/Rehlert.RoP/Extensions/OnErrorExtensions.cs
@@ -0,0 +1,55 @@
+namespace Rehlert.RoP.Extensions;
+
+public static class OnErrorExtensions
+{
+    public static Result<TIn, TErr> OnError<TIn, TErr>(this Result<TIn, TErr> value, Action<TErr> action)
+    {
+        value.Match(
+            _ => { },
+            err => action(err.Value)
+        );
+
+        return value;
+    }
+
+    public static async Task<Result<TIn, TErr>> OnError<TIn, TErr>(
+        this Result<TIn, TErr> value,
+        Func<TErr, Task> func
+    )
+    {
+        await value.Match(
+            _ => Task.CompletedTask,
+            err => func(err.Value)
+        );
+
+        return value;
+    }
+
+    public static async Task<Result<TIn, TErr>> OnError<TIn, TErr>(
+        this Task<Result<TIn, TErr>> value,
+        Func<TErr, Task> func
+    )
+    {
+        var valRes = await value;
+        await valRes.Match(
+            _ => Task.CompletedTask,
+            err => func(err.Value)
+        );
+
+        return valRes;
+    }
+
+    public static async Task<Result<TIn, TErr>> OnError<TIn, TErr>(
+        this Task<Result<TIn, TErr>> value,
+        Action<TErr> action
+    )
+    {
+        var valRes = await value;
+        valRes.Match(
+            _ => { },
+            err => action(err.Value)
+        );
+
+        return valRes;
+    }
+}
\ No newline at end of file
diff --git a/Rehlert.RoP/Extensions/OnSuccessExtensions.cs b/Rehlert.RoP/Extensions/OnSuccessExtensions.cs
new file mode 100644
index 0000000..6e61777
--- /dev/null
+++ b/Rehlert.RoP/Extensions/OnSuccessExtensions.cs
@@ -0,0 +1,118 @@
+namespace Rehlert.RoP.Extensions;
+
+public static class OnSuccessExtensions
+{
+    public static Result<TRes, TErr> OnSuccess<TIn, TErr, TRes>(this Result<TIn, TErr> value,
+        Func<TIn, Result<TRes, TErr>> func)
+    {
+        var result = value.Match(
+            ok => func(ok.Value),
+            err => err.Value
+        );
+
+        return result;
+    }
+
+    public static async Task<Result<TRes, TErr>> OnSuccess<TIn, TErr, TRes>(
+        this Result<TIn, TErr> value,
+        Func<TIn, Task<Result<TRes, TErr>>> func
+    )
+    {
+        var result = await value.Match(
+            ok => func(ok.Value),
+            err => Task.FromResult<Result<TRes, TErr>>(err.Value)
+        );
+
+        return result;
+    }
+
+    public static async Task<Result<TRes, TErr>> OnSuccess<TIn, TErr, TRes>(
+        this Task<Result<TIn, TErr>> value,
+        Func<TIn, Task<Result<TRes, TErr>>> func
+    )
+    {
+        var valRes = await value;
+        var result = await valRes.Match(
+            ok => func(ok.Value),
+            err => Task.FromResult<Result<TRes, TErr>>(err.Value)
+        );
+
+        return result;
+    }
+
+    public static async Task<Result<TRes, TErr>> OnSuccess<TIn, TErr, TRes>(
+        this Task<Result<TIn, TErr>> value,
+        Func<TIn, Result<TRes, TErr>> func
+    )
+    {
+        var valRes = await value;
+        var result = valRes.Match(
+            ok => func(ok.Value),
+            err => err.Value
+        );
+
+        return result;
+    }
+
+    public static async Task OnSuccess<TIn, TErr>(
+        this Task<Result<TIn, TErr>> value,
+        Func<TIn, Task> func
+    )
+    {
+        var valRes = await value;
+        await valRes.Match(
+            ok => func(ok.Value),
+            err => Task.CompletedTask
+        );
+    }
+
+    public static async Task OnSuccess<TIn, TErr>(
+        this Task<Result<TIn, TErr>> value,
+        Action<TIn> action
+    )
+    {
+        var valRes = await value;
+        valRes.Match(
+            ok => action(ok.Value),
+            _ => { }
+        );
+    }
+
+    public static async Task OnSuccess<TIn, TErr>(
+        this Result<TIn, TErr> value,
+        Func<TIn, Task> func
+    )
+    {
+        await value.Match(
+            ok => func(ok.Value),
+            _ => Task.CompletedTask
+        );
+    }
+
+    public static void OnSuccess<TIn, TErr>(
+        this Result<TIn, TErr> value,
+        Action<TIn> action
+    )
+    {
+        value.Match(
+            ok => action(ok.Value),
+            _ => { }
+        );
+    }
+
+    public static Result<(T1, T2), TErr> Combine<T1, T2, TErr>(this Result<T1, TErr> r1, Result<T2, TErr> r2)
+    {
+        if (r1 is Result<T1, TErr>.Error err)
+            return err.Value;
+        if (r2 is Result<T2, TErr>.Error err2)
+            return err2.Value;
+        return (r1.UnwrapOk().Value, r2.UnwrapOk().Value);
+    }
+
+    public static async Task<Result<(T1, T2), TErr>> Combine<T1, T2, TErr>(this Task<Result<T1, TErr>> r1,
+        Result<T2, TErr> r2)
+    {
+        var val = await r1;
+        return val.Combine(r2);
+    }
+}
\ No newline at end of file
diff --git a/Rehlert.RoP/Rehlert.RoP.csproj b/Rehlert.RoP/Rehlert.RoP.csproj
new file mode 100644
index 0000000..32f509e
--- /dev/null
+++ b/Rehlert.RoP/Rehlert.RoP.csproj
@@ -0,0 +1,13 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <TargetFramework>net9.0</TargetFramework>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
+    </PropertyGroup>
+
+    <ItemGroup>
+      <PackageReference Include="Dunet" Version="1.11.3" />
+    </ItemGroup>
+
+</Project>
diff --git a/Rehlert.RoP/Result.cs b/Rehlert.RoP/Result.cs
new file mode 100644
index 0000000..949cb3a
--- /dev/null
+++ b/Rehlert.RoP/Result.cs
@@ -0,0 +1,13 @@
+using Dunet;
+
+namespace Rehlert.RoP;
+
+[Union]
+public partial record Result<TOk, TError>
+    where TOk : notnull
+    where TError : notnull
+{
+    public partial record Ok(TOk Value);
+
+    public partial record Error(TError Value);
+}
\ No newline at end of file