[xigoi]

LINQ weirdly renamed basic FP concepts. Why is the map operation called “Select”? If anything, I'd expect the filter operation to be called that.

[tsimionescu]

It's SQL inspired language, because SQL is far and away more well known, and understandable, than functional programming.

And that is one reason why LINQ is still one of the only functional collections APIs that exposes GroupBy, which is an extremely useful operation.

Edit: correction, LINQ is no longer the only one that introduced GroupBy, but it was probably the first.