title: Rust how to convert from array to std::raw:::Slice
body: <p><code>std::raw::Slice</code> is defined as :</p>
  
  <pre><code>pub struct Slice&lt;T&gt; {
      pub data: *const T,
      pub len: uint,
  }
  </code></pre>
  
  <p>I am trying something like this:</p>
  
  <pre><code>use std::raw::Slice as RawSlice;
  let a = [1i,2,3,4];
  let s : RawSlice&lt;int&gt;= RawSlice{data: a as *const int, 
          len : a.len()};
  </code></pre>
  
  <p>This doesn't compile. <code>error: non-scalar cast: [int, ..4] as *const int</code>. I am basically unable to figure out how to get a pointer to the beginning of the array. </p>
  
  <p>A similar concern is: how to convert from [int] to *const int? </p>