Reversing y-axis in an individual ggplot facet

I'm not sure if that's possible, so I would opt for a solution using the grid.arrange function from the gridExtra package.

library(gridExtra)
library(ggplot2)

dat <- data.frame(type = rep(c('A', 'B'), each = 10), x = 1:10, y = rnorm(20),
                  stringsAsFactors = FALSE)

p_A <- ggplot(subset(dat, type == 'A'), aes(x, y)) + geom_point() + facet_wrap( ~ type, scales = 'free_y')+
    scale_y_continuous(breaks = c(-1,0,1))
p_B <- ggplot(subset(dat, type == 'B'), aes(x, y)) + geom_point() + facet_wrap( ~ type, scales = 'free_y')+
    scale_y_reverse(breaks = c(-1,0,1))

grid.arrange(p_A, p_B, nrow = 1)