Microsoft Releases .NET 9

.NET 9 introduces a range of features and improvements aimed at enhancing performance, security, and developer productivity. Key updates include:

Runtime Enhancements:

• Feature Switches with Trimming Support: New attributes enable defining feature switches, allowing unused code to be excluded during trimming, optimizing application size and performance.
• Dynamic Garbage Collection: The garbage collector now adapts dynamically to application sizes, improving memory management efficiency.

Library Updates:

• System.Text.Json:
  • Support for nullable reference type annotations.
  • Ability to export JSON schemas from types.
  • Options to customize JSON indentation and read multiple root-level JSON values from a single stream.
• LINQ Enhancements: Introduction of CountBy and AggregateBy methods for aggregating state by key without allocating intermediate groupings.
• Cryptography:
  • New one-shot hash method on CryptographicOperations.
  • Introduction of classes utilizing the KMAC algorithm.
• Reflection: Addition of PersistedAssemblyBuilder for saving emitted assemblies, including support for emitting symbol information for debugging.
• TimeSpan Enhancements: New From* methods allow the creation of TimeSpan objects from integers, reducing errors from floating-point imprecision.

SDK and Tooling Improvements:

• Workload Sets: Ensures workloads remain at a specific version until explicitly updated, providing greater control over development environments.
• Tool Roll-Forward Option: Users can now decide if .NET tools should run on newer runtime versions, enhancing flexibility.
• Unit Testing Enhancements: Improved MSBuild integration allows running tests in parallel, optimizing testing workflows.
• NuGet Security Audits: By default, audits now include both direct and transitive package references, bolstering security.
• Terminal Logger: Enabled by default with usability improvements, including summarized counts of failures and warnings at the end of builds.
• MSBuild Script Analyzers ("BuildChecks"): New analyzers help detect defects and regressions in build scripts.
• Analyzer Mismatch Detection: The SDK can detect and adjust for version mismatches between the .NET SDK and MSBuild, preventing potential issues.

Language Updates:

• C# 13:
  • Introduction of params collections.
  • New lock type and semantics.
  • Enhanced method group natural type inference.
  • Implicit indexer access in object initializers.
  • Support for ref locals and unsafe contexts in iterators and async methods.
  • Allowing ref struct types to implement interfaces and as arguments for type parameters in generics.
  • Partial properties and indexers in partial types.
  • Overload resolution priority attribute for better overload selection.
• F# 9:
  • Support for nullable reference types.
  • New discriminated union .Is* properties.
  • Enhancements to active patterns and computation expressions.
  • Various productivity, performance, and tooling improvements.

Framework and Tooling Updates:

• ML.NET 4.0: Adds support for additional tokenizers, including Tiktoken, and models like Llama and CodeGen, enhancing machine learning capabilities.
• .NET Aspire:

ASP.NET Core: 

• .NET MAUI: Focuses on product quality enhancements and introduces new features for cross-platform app development.
• Entity Framework Core: Updates include significant enhancements to the Azure Cosmos DB provider, steps towards AOT compilation, and pre-compiled queries.
• Windows Presentation Foundation (WPF): Adds support for Windows 11 theming and hyphen-based ligatures, improving desktop application aesthetics.

These updates in .NET 9 aim to provide developers with more robust, efficient, and secure tools for modern application development.