Thanks, that's interesting. My own main optimization problem is always reducing the memory usage of large in memory data sets. I found that languages like Java and Python, which don't support structured value types and use references/pointers everywhere, are basically unusable for my my purposes.<p>Now, I wonder whether I could use Lisp for what I do. One basic necessity would be to have a way to define a structure like this<p><pre><code>  struct s {
    int32_t x;
    int32_t y;  
  };
</code></pre>
and then create an array of that type as struct s a[size], which uses exactly size * sizeof(s) bytes in memory. A further requirement would be to have a library of data structures (balanced trees, lists, hash tables) that support storing such structs directly without using pointers everywhere.<p>Do you have any idea whether that could work with SBCL?