Question

I’m new to F#, but when I use verbose syntax
to put a for loop in another one,
it will not compile:

#light "off"

let Multiple9x9 () = 
  for i in 1 .. 9 do
    printf "\n";
    for j in 1 .. 9 do
      let k = i * j;
      printf "%d x %d = %2d " i j k ;
    done;;
  done;;
Multiple9x9 ();;
printf "\n" ;;

I know it will work with #light “on”:

let Multiple9x9 () = 
  for i in 1 .. 9 do
    printf "\n"
    for j in 1 .. 9 do
      let k = i * j
      printf "%d x %d = %2d " i j k
Multiple9x9 ()
printf "\n"

Answer 1

If you’re going to use the verbose syntax you need in after each let binding. Also, you don’t need ;; after done in the inner loop: it makes the outer loop incomplete (cutting off the outer done).

Here’s the corrected code:

let Multiple9x9 () = 
  for i in 1 .. 9 do
    printf "\n";
    for j in 1 .. 9 do
      let k = i * j in
      printf "%d x %d = %2d " i j k;
    done;
  done;;
Multiple9x9 ();;
printf "\n" ;;