Developers have their top System.Linq feature requests implemented

[eiriktsarpalis]

Creating this issue to keep track of System.Linq community feature requests that we are considering for .NET 6.

Done

• Support more arities for Enumerable.Zip. (implementation PR)
• Add an Enumerable.ChunkBy method. (Implementation PR)
• Add a non-enumerating Count method. (Implementation PR)
• Add SingleOrDefault/FirstOrDefault/LastOrDefault overloads that allow specifying a default. (implementation PR)
• LINQ APIs to enable C# 8.0 index and range for IEnumerable. (Implementation PR)
• Add Enumerable.*By operators (DistinctBy, ExceptBy, IntersectBy, UnionBy, MinBy, MaxBy). (implementation PR)

Notes on Potential Breaking Changes

The changes add new method overloads to the System.Linq.Queryable APIs. This is known to break query provider implementations whose reflection code isn't sufficiently strong when looking up methods (cf. dotnet/efcore#24002, #49683). Query provider library authors are advised to ensure that their reflection code is tolerant of future method overload additions, e.g. by using a Type.GetMethod() overload that explicitly accepts the method's parameter types.

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Issue Details

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Creating this issue to keep track of System.Linq community feature requests that we are considering for .NET 6.

Issue	Status	Assignee
Support more arities for Enumerable.Zip	Implementation merged	@huoyaoyuan
Add SingleOrDefault/FirstOrDefault/LastOrDefault overloads that allow specifying a default	API approved	@Foxtrek64
Add an Enumerable.Partition method	Ready for review
Add an Enumerable.ChunkBy method	Ready for review
Add a non-enumerating Count method	Ready for review
LINQ APIs to enable C# 8.0 index and range for IEnumerable	API needs work
Add Enumerable.*By operators (DistinctBy, ExceptBy, IntersectBy, UnionBy, MinBy, MaxBy)	API needs work

Author:	eiriktsarpalis
Assignees:	eiriktsarpalis
Labels:	Priority:3, User Story, area-System.Linq
Milestone:	6.0.0

[MgSam]

Finally! After 14 years LINQ will finally get some attention again!

[GSPP]

This is very important work. The introduction of LINQ was such a boon to productivity on .NET. We were leading the entire industry. Now, some additional innovation is desirable to convert the experiences of a decade into widely useful data-processing methods.

[eiriktsarpalis]

All implementation PRs are now merged. Note that some of the new APIs are pending xml documentation, which I'll be introducing in tandem with work for #48986. cc @carlossanlop

[Thaina]

Sadly this not include #28650

[davidfowl]

@eiriktsarpalis we need to make sure these go into the blog