If %sections won't be large (and by now thinking it won't, it will be), the natural answer to "How do I put this between elements" is join:

print join "\n| ", 
      map { a( {-href => "/$sections{$_}"}, "$_ HOME" ) } 
      sort keys %sections;
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I put a newline before the separator so it shows up at the beginning on the line and the link follows it. That makes for easy reading when you have to look at the source (for instance, to verify it's what you said it should be):

Good luck :)