We just need to wait for Span<T> to mature a bit.

• Parse integers in a string based on an index #16933 - Int32.Parse, Int32.TryParse
  • https://github.com/dotnet/corefx/issues/13892#issuecomment-262382196 - Parse on all primitive types (sbyte.Parse byte.Parse short.Parse ... ulong.Parse, DateTime.Parse, Guid.Parse, etc)
• Add methods to StringBuilder to append ReadOnlySpan<char> #19437 - StringBuilder.Append
• https://github.com/dotnet/corefx/issues/13892#issuecomment-262576835 - ImmutableArray<T>.implicit operator ReadOnlySpan<T>()
• https://github.com/dotnet/corefx/issues/7656#issuecomment-231217120 - string.Split
• https://github.com/dotnet/corefx/issues/12672#issue-183177295 - Guid.GetBytes(out byte[]), Decimal.GetBits(decimal, out byte[])
  • https://github.com/dotnet/corefx/issues/12672#issuecomment-253959625 - Look at all methods which take new array (e.g. out byte[])
• dotnet/corefx#14255 - Encoding.GetBytes
• https://github.com/dotnet/corefx/issues/17281 - SocketAsyncEventArgs.SetBuffer(Memory<T>)
• https://github.com/dotnet/corefx/issues/13892#issuecomment-287667969 - Stream.Read/Write[Async] and Socket.Send/Receive[Async]
• https://github.com/dotnet/corefx/issues/6740#issuecomment-287684217 - IO APIs
• dotnet/corefx#17378 - IPAddress
• dotnet/corefx#18693 - Crypto
• dotnet/corefx#18847 - ImmutableArray.AsReadOnlySpan()