"&" captures references, not copies. I would like it to be just syntactic sugar for "&x, &y, ..." and only include the variables that I actually used in the bod

"&" captures references, not copies. I would like it to be just syntactic sugar for "&x, &y, ..." and only include the variables that I actually used in the body of lambda. There is no performance cost to that (unless a crash is somehow a performance win --- hey, the program finished earlier, I guess it's faster...).