Introduce generic math LINQ operators

[roji]

With generic math coming in C# 11, we can introduce generic versions of math LINQ operators. These would include Average, Sum, Max, Min, and would allow e.g. representing math over date/time types (e.g. TimeSpan).

Note that if we end up implementing an identity ordering operator (without a key selector), as per #14729, we may want to think about what role, if any, IComparisonOperators would play there. In theory, either IComparable or IComparisonOperators is sufficient for such an operator.

Note that this would include both enumerable and queryable versions. I specifically ran into this while considering how to represent a sum of time intervals operation for translation to SQL with EF Core. A generic Sum method would be perfect for that (TimeSpan would also to implement the appropriate interfaces as well).

/cc @tannergooding @ajcvickers

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Issue Details

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With generic math coming in C# 11, we can introduce generic versions of math LINQ operators. These would include Average, Sum, Max, Min, and would allow e.g. representing math over date/time types (e.g. TimeSpan).

Note that if we end up implementing an identity ordering operator (without a key selector), as per #14729, we may want to think about what role, if any, IComparisonOperators would play there. In theory, either IComparable or IComparisonOperators is sufficient for such an operator.

Note that this would include both enumerable and queryable versions. I specifically ran into this while considering how to represent a sum of time intervals operation for translation to SQL with EF Core. A generic Sum method would be perfect for that (TimeSpan would also to implement the appropriate interfaces as well).

Author:	roji
Assignees:	-
Labels:	enhancement, area-System.Linq
Milestone:	-

[stephentoub]

Duplicate of #64031

[roji]

Thanks, somehow missed this in my searches.