title: switching the expected input from string to bool
body: <p>Having the task:
  Write a function <code>printmat : bool array array -&gt; unit = &lt;fun&gt;</code> that
  given a bool matrix it prints it on screen with ones and zeros, instead of
  true and false.</p>
  <pre class="lang-ml prettyprint-override"><code>    # let matrix =[|[| false ; true ; false |];[| true ; false ; false
      |];[| false ; false ; true |];[| false ; false ; false |]|];;
       # printmat matrix ;;
       010
       100
       001
       000
  </code></pre>
  <p>I managed to do this so far:</p>
  <pre class="lang-ml prettyprint-override"><code>
      let matrix = [|
        [|true; true; false; false|];
        [|false; false; true; true|];
        [|true; false; true; false|];
        [|true; false; false; true|]
      |];;
      let print_s matrix =
        let n = Array.length matrix in
        for i = 0 to n - 1 do
          let n1 = Array.length matrix in
          for j = 0 to n1 - 1 do
            print_string matrix.(i).(j);
          done;
          print_string&quot;/n&quot;;
        done;;
  </code></pre>
  <p>But, my function has a type <code>string array array</code> instead of <code>bool array array</code>. It is also affecting the calling of the function since my code only works for the already declared matrix, I can't call a function with the given matrix since it expects bool type.</p>