for_loop_test.ml

let for_3 x = 
  let v = ref 0 in
  let arr = Array.map (fun _ -> fun _ -> ()) x in
  for i = 0 to Array.length x - 1 do 
    let j = i * 2 in
    arr.(i) <- (fun  _ -> v := !v + j)
  done;
  Array.iter (fun x -> x ()) arr;
  !v
    


let for_4 x = 
  let v = ref 0 in
  let arr = Array.map (fun _ -> fun _ -> ()) x in
  for i = 0 to Array.length x - 1 do 
    let j = i * 2 in
    let k = 2 * j in
    arr.(i) <- (fun  _ -> v := !v + k)
  done;
  Array.iter (fun x -> x ()) arr;
  !v

let for_5 x u = 
  let v = ref 0 in
  let arr = Array.map (fun _ -> fun _ -> ()) x in
  for i = 0 to Array.length x - 1 do 
    let _j = i * 2 in
    let k = 2 * u * u in
    arr.(i) <- (fun  _ -> v := !v + k)
  done;
  Array.iter (fun x -> x ()) arr;
  !v


let for_6 x u = 
  let v = ref 0 in
  let arr = Array.map (fun _ -> fun _ -> ()) x in
  let v4 = ref 0 in
  let v5 = ref 0 in
  let inspect_3 = ref (-1) in
  incr v4; 
  for j = 0 to 1 do
    incr v5 ; 
    let v2 = ref 0 in
    let v3 = u in
    for i = 0 to Array.length x - 1 do 
      let _j = i * 2 in
      let k = 2 * u * u in
      let h = 2 * !v5 in
      incr v2; 
      arr.(i) <- (fun  _ -> v := !v + k + !v2  + !v4 + !v5  + h + v3)
          (* v2 should not be captured *)
    done; 
    inspect_3 := !v2;
  done;
  Array.iter (fun x -> x ()) arr;
  [|!v; !v4 ; !v5;  !inspect_3 |]

let for_7 () = 
  let i_len = 7 in
  let j_len = 3 in 
  let v = ref 0 in 
  let arr = Array.make (i_len * j_len) (fun _ -> ()) in
  for i = 0 to i_len - 1 do 
    
    for j = 0 to j_len - 1 do
      arr.(i * j_len + j) <- 
        (fun _ -> 
          begin 
            (* print_endline @@ Printf.sprintf "%d %d" i j; *)
            (* print_endline @@ string_of_int ( i * j_len + j) ^ " "  *)
            (* ^ (string_of_int i) ^ " " ^ string_of_int j; *)
            v:= !v + i + j
          end)
    done
  done;
  Array.iter (fun f -> f ())   arr;
  !v


let for_8 () = 
  let i_len = 7 in
  let j_len = 3 in 
  let v = ref 0 in 
  let arr = Array.make (i_len * j_len) (fun _ -> ()) in
  for i = 0 to i_len - 1 do 
    let k = 2 * i in
    for j = 0 to j_len - 1 do
      let h = i +  j in
      arr.(i * j_len + j) <- 
        (fun _ -> 
          begin 
            (* prerr_endline @@ Printf.sprintf "%d %d" i j; *)
            v:= !v + i + j + h + k
          end)
    done
  done;
  Array.iter (fun f -> f ())   arr;
  !v


let for_9 () = 
  let collect, get = 
  let v : int list ref = ref [] in
  (fun x ->  v := x::!v) , (fun () -> Array.of_list @@ List.rev !v) in

  let i_len = 2 in
  let j_len = 2 in
  let vv = ref 0 in
  let vv2 = ref 0  in
  let arr = Array.make (i_len * j_len ) (fun _ -> ()) in
  let arr2 = Array.make i_len (fun _ -> ()) in
  for i = 0 to i_len - 1 do
    let v = ref 0 in
    (* incr v ;  *)
    v := !v   + i ; 
    for j = 0 to j_len - 1 do
      incr v ;
      collect !v ;
      arr.(i * j_len + j)<- 
      fun _ -> 
        (* prerr_endline @@ Printf.sprintf "<%d" !vv ;  *)
        (* prerr_endline @@ Printf.sprintf ">%d" !vv ;  *)
        vv := !vv + !v; 
        (* v should not be captured inside , 
           since for next iteration, 
           we are bound the same v

           there are four iterations of this function
           
           the first two bound one v 

           the second two bound the other one

           -- sometimes it's hard to tell the difference,  
           when v is not relevant to the outer [index]
           actually we have to lexical scope the whole for statement
         *)

    done;
    arr2.(i) <- fun _ -> vv2 := !vv2 + !v ; 
     (* v should be captured, since next iteration 
        v is changed
      *)
  done;
  Array.iter (fun f -> f ()) arr ;
  Array.iter (fun f -> f ()) arr2 ;
  [| !vv, get(), !vv2
   |]


(**

See how google closure works, in both simple model and advanced model

{[
var x = []

var u = []
var result = 0
for(let i = 0; i < 2; ++i){
  let counter = 0;
  counter += i;
  for(let j = 0; j < 2 ; ++j){
     x[i * 2 +j ] = ()=>{ result += counter}
   }
  u.push(counter)
}
x.forEach(x=>x())
console.log(result,u)
]}


*)

let suites =  [

"for_loop_test_3", (fun  _ -> 
   Mt.Eq (90, (for_3 @@ Array.make 10 2);));
"for_loop_test_4", (fun _ ->
    Mt.Eq (180, (for_4 @@ Array.make 10 2)));
"for_loop_test_5", (fun _ ->
   Mt.Eq(2420, (for_5 (Array.make 10 2) 11)));
"for_loop_test_6", (fun _ ->
  Mt.Eq([|30;1;2;3|], (for_6 (Array.make 3 0 ) 0))
                   );
"for_loop_test_7", (fun _ ->
   Mt.Eq(84, (for_7 ())));

"for_loop_test_8", (fun _ ->
   Mt.Eq(294, (for_8 ())));
"for_loop_test_9", (fun _ -> 
   Mt.Eq([|10,[|1;2;2;3|], 5|], (for_9 ())))
]