Lazy evaluation in R

f <- function(a, b) {
  print('1st value will be printed')
  print(a)
}

f(2, print('ok'))
# Output:
# [1] "1st value will be printed"
# [1] 2

f(print('ok'), 2)
# Output:
# [1] "1st value will be printed"
# [1] "ok"
# [1] "ok"