Initial implementations of the library

.github/workflows/cicd.yml

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+name: Library Release
+
+on:
+  push:
+    branches:
+      - main
+
+permissions:
+  contents: read
+  packages: write
+
+jobs:  
+  build:
+    name: Build and Test
+    runs-on: ubuntu-latest
+    strategy:
+        fail-fast: false
+        matrix:
+          dotnet-version: [6.0.x,7.0.x,8.0.x]
+
+    steps:
+      - name: Checkout Code
+        uses: actions/checkout@v4
+
+      - name: Setup .NET ${{ matrix.dotnet-version }}
+        uses: actions/setup-dotnet@v4
+        with:
+          dotnet-version: ${{ matrix.dotnet-version }}
+
+      - name: Install Dependencies
+        run: dotnet restore
+
+      - name: Build
+        run: dotnet build --configuration Release --no-restore --nologo
+
+      - name: Test
+        run: dotnet test --configuration Release --no-build --no-restore --verbosity normal
+
+  publish:
+      name: Publish Package
+      runs-on: ubuntu-latest
+      needs: build
+      steps:
+        - name: Checkout Code
+          uses: actions/checkout@v4
+          with:
+            fetch-depth: 0
+
+        - name: Setup .NET
+          uses: actions/setup-dotnet@v4
+          with:
+            dotnet-version: 8.0.x
+
+        - name: Install Dependencies
+          run: dotnet restore
+
+        - name: Setup GitFlow
+          uses: gittools/actions/gitversion/setup@v1.1.1
+          with:
+            versionSpec: '5.x'
+
+        - name: Determine Version
+          uses: gittools/actions/gitversion/execute@v1.1.1
+
+        - name: Build
+          run: dotnet build -c Release --no-restore /p:Version="${{ env.GitVersion_SemVer }}-alpha.${{ env.GitVersion_PreReleaseTag }}" /p:AssemblyVersion="${{ env.GitVersion_SemVer }}" /p:FileVersion="${{ env.GitVersion_SemVer }}"
+
+        - name: Pack the Nuget Packages
+          run: dotnet pack -c Release --no-build --no-restore --include-symbols --include-source --output nupkgs /p:PackageVersion="${{ env.GitVersion_SemVer }}-alpha.${{ env.GitVersion_PreReleaseTag }}" 
+
+        - name: Publish the Nuget Packages to the GitHub Package Registry
+          run: dotnet nuget push **/*.nupkg --skip-duplicate --api-key ${{ secrets.GITHUB_TOKEN }} --source "https://nuget.pkg.github.com/deveel/index.json"
+
+  clean:
+    name: Clean Pre-Release Packages
+    needs: publish
+    uses: ./.github/workflows/clean-packages.yml

.github/workflows/clean-packages.yml

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+name: Clean Pre-Release Packages
+
+on:
+  workflow_call:
+  workflow_dispatch:
+
+jobs:
+  clean:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Clean Deveel.Results
+        uses: actions/delete-package-versions@v5
+        with: 
+          package-name: 'Deveel.Results'
+          package-type: 'nuget'
+          min-versions-to-keep: 10
+          delete-only-pre-release-versions: true

.github/workflows/pr-build.yml

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+name: PR Build
+
+on:
+  pull_request:
+      branches:
+      - main
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        dotnet-version: [6.0.x, 7.0.x, 8.0.x]
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Setup .NET
+      uses: actions/setup-dotnet@v4
+      with:
+        dotnet-version: ${{ matrix.dotnet-version }}
+
+    - name: Install dependencies
+      run: dotnet restore
+
+    - name: Build
+      run: dotnet build -c Release --no-restore
+
+    - name: Test
+      run: dotnet test -c Release --no-build --no-restore

Deveel.Results.sln

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+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.0.31903.59
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "src", "src", "{A23FC229-2F71-4F53-BAFE-62C05D1B85F2}"
+EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Deveel.Results", "src\Deveel.Results\Deveel.Results.csproj", "{AF4AA20C-ABEE-41C3-B7FA-660001B3273C}"
+EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "test", "test", "{09824D71-F662-4403-A251-CB5E064CC019}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Deveel.Results.XUnit", "test\Deveel.Results.XUnit\Deveel.Results.XUnit.csproj", "{0B0F8D70-20EC-4B29-8AD3-64047EF50975}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{AF4AA20C-ABEE-41C3-B7FA-660001B3273C}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{AF4AA20C-ABEE-41C3-B7FA-660001B3273C}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{AF4AA20C-ABEE-41C3-B7FA-660001B3273C}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{AF4AA20C-ABEE-41C3-B7FA-660001B3273C}.Release|Any CPU.Build.0 = Release|Any CPU
+		{0B0F8D70-20EC-4B29-8AD3-64047EF50975}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{0B0F8D70-20EC-4B29-8AD3-64047EF50975}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{0B0F8D70-20EC-4B29-8AD3-64047EF50975}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{0B0F8D70-20EC-4B29-8AD3-64047EF50975}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(NestedProjects) = preSolution
+		{AF4AA20C-ABEE-41C3-B7FA-660001B3273C} = {A23FC229-2F71-4F53-BAFE-62C05D1B85F2}
+		{0B0F8D70-20EC-4B29-8AD3-64047EF50975} = {09824D71-F662-4403-A251-CB5E064CC019}
+	EndGlobalSection
+EndGlobal

src/Deveel.Results/Deveel.Results.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFrameworks>net6.0;net7.0;net8.0</TargetFrameworks>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <RootNamespace>Deveel</RootNamespace>
+    <GenerateDocumentationFile>true</GenerateDocumentationFile>
+  </PropertyGroup>
+
+  <PropertyGroup>
+    <Title>Deveel Results</Title>
+    <Description>A simple and unambitious library to implement the result pattern in services.</Description>
+    <PackageTags>result;results;operation;pattern;error;domain;ddd;domain-driven</PackageTags>
+  </PropertyGroup>
+
+</Project>

src/Deveel.Results/IOperationError.cs

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+namespace Deveel
+{
+    /// <summary>
+    /// Represents an error that occurred during an operation.
+    /// </summary>
+    public interface IOperationError
+    {
+        /// <summary>
+        /// Gets the unique code of the error
+        /// within the domain of the operation.
+        /// </summary>
+        string Code { get; }
+
+        /// <summary>
+        /// Gets the domain of the operation
+        /// where the error occurred.
+        /// </summary>
+        string Domain { get; }
+
+        /// <summary>
+        /// Gets the message that describes the error.
+        /// </summary>
+        string? Message { get; }
+
+        /// <summary>
+        /// Gets an inner error that caused this error.
+        /// </summary>
+        IOperationError? InnerError { get; }
+    }
+}

src/Deveel.Results/IOperationResult.cs

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+namespace Deveel
+{
+    /// <summary>
+    /// Represents the result of an operation.
+    /// </summary>
+    public interface IOperationResult
+    {
+        /// <summary>
+        /// Gets the type of the result of the operation.
+        /// </summary>
+        OperationResultType ResultType { get; }
+
+        /// <summary>
+        /// When the result is a failure, gets the error 
+        /// that caused the operation to fail.
+        /// </summary>
+        IOperationError? Error { get; }
+    }
+}

src/Deveel.Results/IOperationResult_T.cs

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+namespace Deveel
+{
+    /// <summary>
+    /// Represents the result of an operation that
+    /// has a value returned.
+    /// </summary>
+    /// <typeparam name="T"></typeparam>
+    public interface IOperationResult<T> : IOperationResult
+    {
+        /// <summary>
+        /// Gets the value returned by an operation.
+        /// </summary>
+        T? Value { get; }
+    }
+}

src/Deveel.Results/OperationError.cs

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+namespace Deveel
+{
+    /// <summary>
+    /// Implements a simple error object that can be used to represent
+    /// a failure in an operation.
+    /// </summary>
+    public readonly struct OperationError : IOperationError
+    {
+        /// <summary>
+        /// Constructs an instance of an <see cref="OperationError"/> object.
+        /// </summary>
+        /// <param name="code">
+        /// The code of the error, that is unique within the 
+        /// given domain.
+        /// </param>
+        /// <param name="domain">
+        /// The domain where the error occurred.
+        /// </param>
+        /// <param name="message">
+        /// A message that describes the error.
+        /// </param>
+        /// <param name="innerError">
+        /// A reference to an inner error that caused this error.
+        /// </param>
+        /// <exception cref="ArgumentNullException">
+        /// Thrown when the <paramref name="code"/> or <paramref name="domain"/>
+        /// are <see langword="null"/>.
+        /// </exception>
+        public OperationError(string code, string domain, string? message = null, IOperationError? innerError = null)
+        {
+            ArgumentNullException.ThrowIfNull(code, nameof(code));
+            ArgumentNullException.ThrowIfNull(domain, nameof(domain));
+
+            Code = code;
+            Domain = domain;
+            Message = message;
+            InnerError = innerError;
+        }
+
+        /// <inheritdoc />
+        public string Code { get; }
+
+        /// <inheritdoc />
+        public string Domain { get; }
+
+        /// <inheritdoc />
+        public string? Message { get; }
+
+        /// <inheritdoc />
+        public IOperationError? InnerError { get; }
+    }
+}

src/Deveel.Results/OperationException.cs

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+// Non-nullable field must contain a non-null value when exiting constructor.
+#pragma warning disable CS8618
+
+namespace Deveel
+{
+    /// <summary>
+    /// An exception that represents an unhandled error that has 
+    /// occurred during an operation.
+    /// </summary>
+    public class OperationException : Exception, IOperationError
+    {
+        /// <summary>
+        /// Constructs an instance of an <see cref="OperationException"/> with
+        /// the specified error code and domain.
+        /// </summary>
+        /// <param name="errorCode">
+        /// The unique code that identifies the error within the domain.
+        /// </param>
+        /// <param name="errorDomain">
+        /// The domain where the error has occurred.
+        /// </param>
+        public OperationException(string errorCode, string errorDomain)
+        {
+            SetErrorDetails(errorCode, errorDomain);
+        }
+
+        /// <summary>
+        /// Constructs an instance of an <see cref="OperationException"/> with
+        /// the specified error code and domain.
+        /// </summary>
+        /// <param name="errorCode">
+        /// The unique code that identifies the error within the domain.
+        /// </param>
+        /// <param name="errorDomain">
+        /// The domain where the error has occurred.
+        /// </param>
+        /// <param name="message">
+        /// A message that describes the error.
+        /// </param>
+        public OperationException(string errorCode, string errorDomain, string? message)
+            : base(message)
+        {
+            SetErrorDetails(errorCode, errorDomain);
+        }
+
+        /// <summary>
+        /// Constructs an instance of an <see cref="OperationException"/> with
+        /// the specified error code and domain.
+        /// </summary>
+        /// <param name="errorCode">
+        /// The unique code that identifies the error within the domain.
+        /// </param>
+        /// <param name="errorDomain">
+        /// The domain where the error has occurred.
+        /// </param>
+        /// <param name="message">
+        /// A message that describes the error.
+        /// </param>
+        /// <param name="innerException">
+        /// An exception that has caused the error.
+        /// </param>
+        public OperationException(string errorCode, string errorDomain, string? message, Exception? innerException)
+            : base(message, innerException)
+        {
+            SetErrorDetails(errorCode, errorDomain);
+        }
+
+        /// <summary>
+        /// The unique code that identifies the error within the domain.
+        /// </summary>
+        public string ErrorCode { get; private set; }
+
+        string IOperationError.Code => ErrorCode;
+
+        /// <summary>
+        /// The domain where the error has occurred.
+        /// </summary>
+        public string ErrorDomain { get; private set; }
+
+        string IOperationError.Domain => ErrorDomain;
+
+        IOperationError? IOperationError.InnerError => InnerException as IOperationError;
+
+        private void SetErrorDetails(string errorCode, string errorDomain)
+        {
+            ArgumentNullException.ThrowIfNull(errorCode, nameof(errorCode));
+            ArgumentNullException.ThrowIfNull(errorDomain, nameof(errorDomain));
+
+            ErrorCode = errorCode;
+            ErrorDomain = errorDomain;
+
+            Data[nameof(ErrorCode)] = errorCode;
+            Data[nameof(ErrorDomain)] = errorDomain;
+        }
+    }
+}