title: Convert a sequence of dictionary keys to a set
body: <p>The following code lists the  set of keys found in a dictionary sequence (each dict is basically a row from a database). (I want to convert the keys to a set so I can compare 2 db tables)</p>
  
  <pre><code>for seqitem in tblseq do
      let keyset = seqitem.Keys |&gt; Set.ofSeq    // works correctly
      printfn "&gt;&gt;&gt; List: %A; Item Type: %A" keyset
  </code></pre>
  
  <p>Rather than print the keyset however I want to return it from a function but am having a problem with type inference. Tried the following but it does not work;</p>
  
  <p>What I want to do is return these values as either an array of list (rather than print them)</p>
  
  <pre><code>let get_keyset tblseq = 
                  tblseq |&gt; Seq.iter (fun x -&gt;  
                         x.Keys |&gt; Set.ofSeq                   
                       ) 
  </code></pre>
  
  <p>What am I missing here?</p>