The only differences I see between filter(a > mean(a)) and @where_vec(:a .> mean(:a)) (JuliaDBMeta, just like dpyr, has a curried version) is the use of symbols to refer to columns and of dot broadcasting for element-wise comparison. I’m really not sure how one can avoid using symbols and just put variable names. Dot broadcasting is necessary because, if we are taking mean(a) it means a is a vector and thus we need to compare element-wise.
The example is in my view interesting because it shows a case where automatic dot broadcasting would not work with @where in DataFrames as one would get v .> mean.(v) which is not the correct thing.