add benchmarks for tiny_rope in bench folder

bench/run.sml

@@ -14,40 +14,9 @@ struct
       Vector.foldl folder Txn.empty Txn.txns
   end
 
-  fun runTxnsTime () =
-    let
-      val startTime = Time.now ()
-      val startTime = Time.toMilliseconds startTime
-
-      val x = runTxns ()
-
-      val endTime = Time.now ()
-      val endTime = Time.toMilliseconds endTime
-
-      val timeDiff = endTime - startTime
-      val timeDiff = LargeInt.toString timeDiff
-      val timeTook = String.concat [timeDiff, " ms taken for " ^ Txn.title ^ " txns\n"]
-      val _ = (print timeTook)
-    in
-      x
-    end
-
-  fun write (fileName, buffer) =
-    let
-      val str = Txn.toString buffer
-      val io = TextIO.openOut fileName
-      val _ = TextIO.output (io, str)
-      val _ = TextIO.closeOut io
-    in
-      ()
-    end
-
   fun run () =
     let
-      val buffer = runTxnsTime ()
-      (* The write operation guarantees that MLton doesn't optimise away the
-       * buffer's contents, because it has to write the contents to a file. *)
-      val _ = write ("out/" ^ Txn.title ^ ".txt", buffer)
+      val buffer = runTxns ()
     in
       ()
     end