Pros of runtime

• More actively maintained and developed
• Open-source with community contributions
• Supports cross-platform development (.NET Core)

Cons of runtime

• Larger codebase, potentially more complex to navigate
• May have more frequent changes, requiring developers to stay updated

Code Comparison

referencesource:

public static int IndexOf(string source, string value, int startIndex, int count)
{
    return IndexOf(source, value, startIndex, count, StringComparison.CurrentCulture);
}

runtime:

public static int IndexOf(string source, string value, int startIndex, int count, StringComparison comparisonType)
{
    if (source == null)
        throw new ArgumentNullException(nameof(source));
    if (value == null)
        throw new ArgumentNullException(nameof(value));

    return IndexOfCore(source, value, startIndex, count, comparisonType);
}

The runtime version includes additional null checks and uses a separate core method for implementation, potentially offering better error handling and modularity.

Pros of mono

• Open-source implementation of .NET Framework, allowing for greater community involvement and contributions
• Cross-platform support, enabling development for various operating systems beyond Windows
• More frequent updates and releases, potentially incorporating new features faster

Cons of mono

• May have compatibility issues with some Windows-specific .NET features
• Smaller ecosystem and community compared to the official Microsoft implementation
• Potentially less stable or optimized for certain use cases

Code Comparison

referencesource:

public static string Format(string format, object arg0)
{
    return Format(null, format, new object[] { arg0 });
}

mono:

public static string Format(string format, object arg0)
{
    return Format(format, new object[] { arg0 });
}

The code snippets show a minor difference in the implementation of the Format method. The mono version omits the null parameter present in the referencesource version, which likely represents a culture-specific formatting option.

Pros of coreclr

• Open-source and community-driven development
• Cross-platform support (Windows, macOS, Linux)
• Optimized for cloud and containerized environments

Cons of coreclr

• Smaller ecosystem compared to the full .NET Framework
• Some legacy APIs and features not supported
• Potential compatibility issues with older .NET applications

Code Comparison

referencesource:

public static void Main(string[] args)
{
    Console.WriteLine("Hello, World!");
}

coreclr:

public static void Main(string[] args)
{
    Console.WriteLine("Hello, World!");
}

The basic structure and syntax remain the same in both repositories. However, coreclr may include additional optimizations and cross-platform considerations in its implementation.

Summary

coreclr represents the open-source, cross-platform evolution of the .NET runtime, while referencesource provides the reference implementation for the full .NET Framework. coreclr offers better support for modern development practices and environments, but may lack some features present in the full framework. Both repositories maintain similar code structure and syntax for core functionality.

Pros of corefx

• Open-source and community-driven development
• Cross-platform support (Windows, macOS, Linux)
• More frequent updates and improvements

Cons of corefx

• Potentially less stable due to rapid development
• May lack some legacy Windows-specific features
• Learning curve for developers transitioning from referencesource

Code Comparison

referencesource:

public static string Format(string format, object arg0)
{
    return Format(null, format, new object[] { arg0 });
}

corefx:

public static string Format(string format, object arg0)
{
    return Format(null, format, arg0);
}

The corefx implementation is more concise, avoiding the creation of an unnecessary object array. This reflects the overall trend of performance optimizations in corefx.

Both repositories serve as valuable resources for .NET developers, with referencesource providing a stable reference for the .NET Framework, and corefx offering a more modern, cross-platform approach to .NET development. The choice between them depends on specific project requirements and target platforms.

Pros of Roslyn

• Open-source compiler with a more modern, extensible architecture
• Provides powerful APIs for code analysis and manipulation
• Supports newer C# language features and compilation targets

Cons of Roslyn

• Larger codebase, potentially more complex to navigate
• May have a steeper learning curve for contributors
• Some legacy .NET Framework components not included

Code Comparison

Roslyn (C# compiler implementation):

public override BoundNode VisitMethodDeclaration(MethodDeclarationSyntax node)
{
    var symbol = (MethodSymbol)this.GetDeclaredSymbol(node);
    return new BoundMethodDeclaration(node, symbol, null);
}

ReferenceSource (.NET Framework implementation):

public virtual MethodInfo GetMethod(String name)
{
    return GetMethod(name, Type.DefaultLookup);
}

Summary

Roslyn represents a more modern, open-source approach to the C# compiler, offering extensive APIs for code analysis and manipulation. It supports newer language features but has a larger, potentially more complex codebase. ReferenceSource provides a view into the .NET Framework's implementation, which may be simpler in some areas but lacks the extensibility and openness of Roslyn.

Pros of csharplang

• Focuses specifically on C# language design and proposals
• More active community involvement and discussions
• Provides detailed explanations of language features and their rationale

Cons of csharplang

• Limited to language specifications and proposals
• Doesn't include actual implementation code
• May be more challenging for beginners to understand and contribute

Code Comparison

csharplang (proposal example):

public static class StringExtensions
{
    public static bool IsNullOrEmpty([NotNullWhen(false)] this string? s) =>
        string.IsNullOrEmpty(s);
}

referencesource (implementation example):

public static class String {
    public static bool IsNullOrEmpty(String value) {
        return (value == null || value.Length == 0);
    }
}

The csharplang example shows a proposed extension method with nullable reference types, while the referencesource example displays the actual implementation of the IsNullOrEmpty method in the .NET Framework.