[Feature] Span<T>

[JRAlexander]

Span<T>

This topic will address how to work with Span and related types. Span is a new type we are adding to the platform to represent contiguous regions of arbitrary memory, with performance characteristics on par with T[]. Its APIs are similar to the array, but unlike arrays, it can point to either managed or native memory, or to memory allocated on the stack.

Still Needed:

• Content Types
• Table of Contents
• Prioritization

[davidfowl]

/cc @KrzysztofCwalina @stephentoub @jkotas @benadams

[joshfree]

@ahsonkhan @GrabYourPitchforks

[JimBobSquarePants]

Current 2.0 Docs are picking up on the obsolete attribute which is causing confusion.

https://docs.microsoft.com/en-us/dotnet/api/system.span-1?view=netcore-2.0

[mairaw]

Thanks @JimBobSquarePants. This seems related to the following issues that we're tracking:
https://github.com/dotnet/docs/issues/1876
mono/api-doc-tools#76

@weshaggard I see that the obsolete attribute was added with the addition of the .NET Core 2.1 reference assemblies. Is Span<T> really marked as obsolete in 2.1?

[JimBobSquarePants]

@mairaw See the below link for reasoning behind the obsolete attribute

https://github.com/dotnet/csharplang/blob/master/proposals/csharp-7.2/span-safety.md#metadata-representation-or-ref-like-structs

[ahsonkhan]

cc @VSadov

[mairaw]

I've created a workaround PR to fix the obsolete attribute issue while the true fix is being worked out:
dotnet/dotnet-api-docs#49

[OnurGumus]

@mairaw Obsolete attribute blocks the F# compiler for span.

[mairaw]

@cartermp can you look at this previous comment?

[cartermp]

It doesn't affect these docs. When we take a look at proper span support in the F# compiler that particular issue will be addressed.

[OnurGumus]

Perhaps this is not correct place to rant but there is a tendency to treat C#== .NET. It seems for BCL and runtime changes languages like F# is completely ignored or afterthought. Same things happened with .NET Native, ValueTuple, default interface implementations etc. I just wish things were more lang agnostic.