C# 14: More Implicit Conversions for Span<T> and ReadOnlySpan<T>
Introduction
Span<T> and ReadOnlySpan<T> have become core building blocks for high-performance .NET code.
They’re fast, allocation-free, and great for data processing… but let’s be honest: working with them hasn’t always been the smoothest experience. In many cases, you had to sprinkle .AsSpan() everywhere just to satisfy the compiler. Not a huge deal, but not exactly elegant either. C# 14 makes this much nicer by adding new implicit conversions that let you work with spans more naturally, without all the extra ceremony.
Before C# 14: Too Many Explicit Conversions
If you’ve written span-heavy code before, you’ve probably done something like this:
It worked, but it felt repetitive. And converting lists usually required an array allocation, which defeated the purpose.
What’s New
C# 14 now performs several span conversions automatically. You get implicit conversions from:
- T[] -> Span<T>
- T[] -> ReadOnlySpan<T>
- List<T> -> ReadOnlySpan<T>
- Memory<T> -> span types
- Slice expressions ([..], [^1], etc.) -> spans
The idea is simple: If a type can reasonably be treated as a span, C# 14 will handle it for you.
A Practical Example
Here’s a tiny example using an audio buffer:
As you can see there is no helper methods, no array allocations, just a smooth conversion.
Why It Matters
1- Cleaner, more readable code
Your intent stands out because you’re not cluttering method calls with .AsSpan().
2- No extra allocations
Implicit conversions do not copy data. They simply reinterpret it.
3- Easier adoption of span-centric APIs
The friction is gone, and calling span-based methods feels natural.
Conclusion
This isn’t a headline feature, but it’s one of those small improvements that makes C# nicer to use day after day. Span-based APIs become cleaner, boilerplate disappears, and you get the performance benefits without constantly thinking about conversions. A simple, polished quality-of-life upgrade for modern .NET development.
