title: OCaml : filter map and put the values into a list
body: <p>I can filter my <a href="http://caml.inria.fr/pub/docs/manual-ocaml/libref/Map.Make.html" rel="nofollow">map</a> by key : </p>
  
  <pre><code>module PairKeys =
  struct
    type t = string * string
    let compare (x0,y0) (x1,y1) =
      match String.compare x0 x1 with
      | 0 -&gt; String.compare y0 y1
      | c -&gt; c
  end
  
  module StringMap = Map.Make(PairKeys);;
  ....
  
  let put_key_values_into_a_list (key_searched : string) = 
      StringMap.filter (fun key -&gt; key = key_searched)
  (* should return a list of the values in the filtered map *)
  </code></pre>
  
  <p>After that, I want to put the values into a list. 
  How can I do this in OCaml? </p>
  
  <p>Map.Make documentation : 
  <a href="http://caml.inria.fr/pub/docs/manual-ocaml/libref/Map.Make.html" rel="nofollow">http://caml.inria.fr/pub/docs/manual-ocaml/libref/Map.Make.html</a></p>
  
  <p>Thanks </p>