Printing verbosity

Default verbose = 0:

1:5  # a visible value

#> [1] 1 2 3 4 5

x = 1 + 1  # invisible
for (i in 1:10) i^2  # for loop returns invisible NULL
y = x^2  # invisible

verbose = 1 always prints the last value:

1:5  # a visible value

#> [1] 1 2 3 4 5

x = 1 + 1  # invisible
for (i in 1:10) i^2  # for loop returns invisible NULL
y = x^2  # invisible

#> [1] 4

verbose = 2 prints all invisible values (except for NULL):

1:5  # a visible value

#> [1] 1 2 3 4 5

x = 1 + 1  # invisible

#> [1] 2

for (i in 1:10) i^2  # for loop returns invisible NULL
y = x^2  # invisible

#> [1] 4