Pairwise Enumerable Extensions

[Eregerog]

These extension methods would be similar to existing ones, but provide the element and the previous element as parameters of the function. This should apply to the following methods: ForEachPairwise<T>(Action<T,T> action) AnyPairwise<T>(Func<T,T,bool> predicate) SelectPairwise<T,TRes>(Func<T,T,TRes> selector) WherePairwise<T>(Func<T,T,bool> predicate) and perhaps other extension methods

[XDracam]

Is this a sliding or grouping operation?

Sliding: [0, 1], [1, 2], [2, 3] Grouping: [0, 1], [2, 3]

What we could provide instead is this feature:

IEnumerable<IEnumerable<A>> Grouped<A>(this IEnumerable<A> enumerable, uint groupSize)
IEnumerable<IEnumerable<A>> Sliding<A>(this IEnumerable<A> enumerable, uint slideSize)

These would allow you to do all of your use cases in a generic fashion. What we could then do is following C#7+ only feature:

IEnumerable<(A, A)> PairwiseGrouped<A>(this IEnumerable<A> enumerable, uint groupSize)
IEnumerable<(A, A)> PairwiseSliding<A>(this IEnumerable<A> enumerable, uint slideSize)

Another convenience feature for C#7 which could follow is tuple-deconstructing LINQ methods, which would address the problem of missing deconstruction in function parameter declaration:

IEnumerable<C> Select<A, B, C>(this IEnumerable<(A, B)>, Func<A, B, C> mapping)
IEnumerable<(A, B)> Where<A, B>(this IEnumerable<(A, B)>, Func<A, B, bool> predicate)
// etc pp, maybe for 3-tuple as well

The last one would need an additional issue

[Eregerog]

The Grouping and Sliding sounds like a generic way of what i wanted. The pairwise grouping/sliding also sounds good