Ocaml et conditions imbriquées

val comp   : 'a array -> 'a array -> bool = <fun>     
val plongt : 'a array -> int -> int array = <fun>     
val max    : int -> int -> int = <fun>     

let soustraction t1 t2 =     
   if comp t2 t1     
   then     
      begin     
         let m = max (Array.length t1) (Array.length t2) in     
              
         let tt1 = plongt t1 m      
         and tt2 = plongt t2 m     
         and t3 = Array.make (m+1) 0 in     
           
         for i=0 to m-1 do     
            if (tt1.(i) < tt2.(i))     
            then     
               begin     
                  t3.(i) <- t3.(i) + ((tt1.(i) + 1000) - tt2.(i));     
                  t3.(i+1) <- (-1); 
               end     
            else     
               t3.(i) <- (t3.(i) + (tt1.(i) - tt2.(i)));     
         done;     
           
         t3;     
      end     
   else      
      [|-1|];;

let soustraction t1 t2 =	let M = max (vect_length t1) (vect_length t2) in
	let tt1 = plongt t1 M in 
	let tt2 = plongt t2 M in 
	let t3 = make_vect (M + 1) 0 in
	if comp t2 t1 then
	begin
		for i = 0 to (M - 1) do
		begin
			if (tt1.(i) < tt2.(i)) then
			begin
				
				t3.(i) <- t3.(i) + ((tt1.(i) + 1000) - tt2.(i));
				t3.(i+1) <- (-1)
				
			end
			else
			begin
				
				t3.(i) <- (t3.(i) + (tt1.(i) - tt2.(i)))
				
			end
		end
		done;
	end
	else 
	begin
		t3.(0) <- (-1)
	end

#Entrée interactive:
>								t3.(0) <- (-1)
>								^^^^^^^^^^^^^^
Cette expression n'est pas une fonction, elle ne peut être appliquée.