resource fiddle_string()
   const WIDTH := 70, HEIGHT := 20
   var line : string[WIDTH]
   var screen[1:HEIGHT, 1:WIDTH] : char := ([HEIGHT] ([WIDTH] ' '))
   var line_length : int
   var where : int
   where := 0
   do read(line) != EOF ->
      line_length := length(line)
      where++
# The following line works.
#     fa j := 1 to line_length -> screen[where, j] := line[j] af
# But the next line is equivalent to the above.
      screen[where, 1:line_length] := chars(line)
   od
   if where = 0 -> stop fi
   fa i := 1 to where ->
      writes(i, ": ", screen[i], "\n")
   af
   stop
end fiddle_string

/* ............... Example compile and run(s)

% sr -o fiddle_string fiddle_string.sr
% ./fiddle_string
12345
abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ12345678901234567890
This is the last line.
^D
1: 12345
2: abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ123456789012345678
3: 90
4: This is the last line.
                                              */