add some util functions

proj.mlb

@@ -10,3 +10,4 @@ in
 end
 
 rope.sml
+utils.sml

utils.sml

@@ -0,0 +1,35 @@
+fun time_func title f =
+  let
+    val title = String.concat ["Starting " , title , "..."]
+    val _ = (print title)
+    val start_time = Time.now()
+    val start_time = Time.toMilliseconds start_time
+    val x = f()
+    val end_time = Time.now()
+    val end_time = Time.toMilliseconds end_time
+    val time_diff = end_time - start_time 
+    val time_diff = LargeInt.toString time_diff
+    val time_took = String.concat ["took", time_diff, " ms\n"]
+    val _ = (print time_took)
+  in
+    x
+  end
+
+fun run_txns arr =
+  Vector.foldl 
+    (fn ((pos, del_num, ins_str), rope) =>
+      let
+        val rope = if del_num > 0 then delete pos del_num rope else rope
+        val str_size = String.size ins_str
+        val rope = if str_size > 0 then insert pos ins_str rope else rope
+      in
+        rope
+      end) 
+    empty arr
+
+fun run_txns_time title arr = 
+  let
+    val f = (fn () => run_txns arr)
+  in
+    time_func title f
+  end