📘 ModernBCL.Core.BLC

Modern Polyfills for Legacy .NET Framework 4.8 / 4.8.1

ModernBCL.Core.BLC brings high-performance, zero-allocation replacements for missing modern BCL APIs to legacy .NET Framework apps — enabling performance, safety, and clarity normally available only in .NET 7/8.

This library is especially useful for:

• Enterprise systems that must stay on .NET Framework 4.8 / 4.8.1
• Developers wanting modern BCL APIs and patterns on legacy frameworks
• Teams needing high-quality hashing, guard clauses, or modern date APIs
• Projects migrating from .NET Framework → .NET, but needing behavioral parity

---

🎯 Project Goals

✔ High-performance hashing

• Drop-in System.HashCode polyfill (Framework-only)
• HashAccumulator (32-bit) and HashAccumulator64 (64-bit)
• Order-sensitive, deterministic hashing
• Zero allocations

✔ Modern guard clauses

• Fluent Guard.Against() API
• Polyfilled [CallerArgumentExpression]
• Cleaner constructors and APIs

✔ Modern date & time APIs

• System.DateOnly
• System.TimeOnly

✔ Index / Range polyfills

• System.Index
• System.Range
• Compiler-compatible (supports lowering rules)

✔ Modern slicing helpers

Unified slicing helpers layered on top of Index / Range:

using ModernBCL.Core.Slicing; var slice = data.Slice( Index.FromStart(1), Index.FromEnd(1) );

Equivalent to in C# 8+.