Hi, Guys, I'm learning Advanced R book, when I looked into Evaluation Chapter, I wanna test to create my own transform function, but I encountered problem when using primitive subsetting and assignment function [[<-
rm(list = ls())
df <- mtcars
`[[<-`(df, 'mpg', value = rlang::eval_tidy(expr(-mpg), data = df))
df %>% pull(mpg)
I believe that I will get a negative mpg column, but after subsetting and assignment, I couldn't get what I want