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copied!<p>It's not clear exactly what you're looking for. The default case for structures is a record type with a fixed number of slots, each of which has a name, and is accessible through a function generated by the <code>defstruct</code> macro. E.g., once you've done</p> <pre><code>(defstruct node label) </code></pre> <p>you can access a <code>node</code>'s label with <code>node-label</code> and get fast lookup time (since it's typically just an index into a memory chunk). Now, as you're doing, you can opt to use lists as the implementation of structures, in which case <code>node-label</code> is just an alias for <code>car</code> or <code>first</code>.</p> <pre><code>(defstruct (node (:type list)) label) CL-USER> (make-node :label 'some-label) (SOME-LABEL) CL-USER> (node-label (make-node :label 'some-label)) SOME-LABEL CL-USER> (first (make-node :label 'some-label)) SOME-LABEL CL-USER> (car (make-node :label 'some-label)) </code></pre> <p>If you're looking for arbitrary list-based key value pairs, you probably want a <a href="http://clhs.lisp.se/Body/26_glo_p.htm#property_list">property list</a>, for which Common Lisp contains some convenience functions. </p> <p>If you want to have a structure that also contains a property list, you could add a special constructor populate that list. For instance, </p> <pre><code>(defstruct (node (:type list) (:constructor make-node (label &rest plist))) label plist) CL-USER> (make-node 'some-label :one 1 :two 2) (SOME-LABEL (:ONE 1 :TWO 2)) CL-USER> (node-plist (make-node 'some-label :one 1 :two 2)) (:ONE 1 :TWO 2) </code></pre>

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