julia> using DataTools: oncol, modifying, averaging
julia> using Transducers: Filter
julia> data = [(a = 1, b = 7), (a = 2, b = 3), (a = 3, b = 4)];
julia> rf = oncol(a = +, b = averaging);
julia> foldl(rf, Filter(x -> isodd(x.a)), data)
(a = 4, b = 5.5)
julia> map(modifying(a = string), data)
3-element Array{NamedTuple{(:a, :b),Tuple{String,Int64}},1}:
(a = "1", b = 7)
(a = "2", b = 3)
(a = "3", b = 4)
julia> reduce(modifying(a = +), data)
(a = 6, b = 7)
julia> using Accessors: @optic
julia> data = [(a = ((b = 1,), 2),), (a = ((b = 3,), 4),)];
julia> map(modifying(@optic(_.a[1].b) => x -> 10x), data)
2-element Array{NamedTuple{(:a,),Tuple{Tuple{NamedTuple{(:b,),Tuple{Int64}},Int64}}},1}:
(a = ((b = 10,), 2),)
(a = ((b = 30,), 4),)