title: Execute a line of history in scala REPL
body: <p>The </p>
  
  <pre><code>:history
  </code></pre>
  
  <p>and </p>
  
  <pre><code>:h?
  </code></pre>
  
  <p>e.g. view and search the REPL history:</p>
  
  <pre><code>scala&gt; :h? req
  
  19 :require /git/BIDMach/BIDMach.jar
  20 :require /git/BIDMat/BIDMat.jar
  21 :require /git/BIDMach_Spark/BIDMach_Spark.jar
  27 :require /git/BIDMach_Spark/BIDMatHDFS.jar
  28 :require /git/BIDMach_Spark/BIDMach_Spark.jar
  </code></pre>
  
  <p>Show last K entries:</p>
  
  <pre><code>:history 10
  
   26  :load /git/BIDMach_Spark/scripts/KMeansLearner.ssc
   27  :require /git/BIDMach_Spark/BIDMatHDFS.jar
   28  :require /git/BIDMach_Spark/BIDMach_Spark.jar
   29  :require /git/BIDMach/BIDMach.jar
   30  :load /git/BIDMach_Spark/scripts/KMeansLearner.ssc
   31  :q
   32  :require /git/BIDMat/BIDMat.jar
   33  :?
   34  :help
   35  :h?
  </code></pre>
  
  <p>How do we <em>execute</em> the numbered history entry?</p>
  
  <p>Following has been tried</p>
  
  <pre><code> :!29
  
   :history 29
  
   :29
  </code></pre>
  
  <p>Does this support exist? Or just supposed to cut and paste?</p>