fix bug in not properly updating squares vector

fcore/app-with.sml

@@ -2,6 +2,24 @@ structure AppWith =
 struct
   open AppType
 
+  fun toList vec = Vector.foldr (fn (el, acc) => el :: acc) [] vec
+
+  fun squaresToString squares =
+  let
+    val vec =
+      Vector.map (fn vec =>
+      let
+        val vec = Vector.map (fn num => Int.toString num) vec
+        val vec: string list = toList vec
+      in
+        String.concat vec
+      end
+      ) squares
+    val vec = toList vec
+  in
+    String.concatWith "\n" vec
+  end
+
   fun addSquare (app, newX, newY, arrowX, arrowY) : app_type =
     let
       val
@@ -28,6 +46,7 @@ struct
         , modalNum
         } = app
 
+      val () = print "adding new square\n"
       val squares =
         Vector.mapi
           (fn (idx, el) =>
@@ -35,6 +54,9 @@ struct
                Vector.mapi (fn (iidx, iel) => if iidx = newY then 1 else iel) el
              else
                el) squares
+
+        val msg = squaresToString squares
+      val () = print (msg ^ "\n")
     in
       { mode = mode
       , squares = squares