dplyr + ggplot2: Plotting not working via piping

I usually do this, which also dispenses with the need for the .:

library(dplyr)
library(ggplot2)

mtcars %>% 
  filter(cyl == 4) %>%
  ggplot +
  aes(
    x = disp,
    y = mpg
  ) + 
  geom_point()

Solution for version 2: a dot . instead of data:

data %>% 
    filter(type=="type1") %>% 
    ggplot(., aes(x=year, y=variable)) + 
    geom_line()