title: Writing and reading to a memory mapped file in OCaml
body: <p>I am experimenting in OCaml to see how I can read/write a numerical array to/from a memory mapped file.</p>
  
  <p>I think I'll need to use Bigarray but not sure how to write down a Bigarray array to a memory mapped file, and then read it back?</p>
  
  <p>I cannot seem to find an example anywhere. I have checked the source code of Jane St. core but to no avail.</p>