screwlisp<p>I think <a href="https://mastodon.sdf.org/tags/CLML" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>CLML</span></a> and <span class="h-card"><a href="https://mastodon.tymoon.eu/@shinmera" class="u-url mention" rel="nofollow noopener noreferrer" target="_blank">@<span>shinmera</span></a></span> get this wrong:<br>You can't (well, shouldn't) do this in <a href="https://mastodon.sdf.org/tags/CommonLisp" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>CommonLisp</span></a> :<br>(defclass my-array () ((actual-array) (element-types) (dimensions)))<br>because you end up with a garbage type. Instead I think:<br>(deftype arrayish (&optional type size) `(and (array type size) (satisfies some-predicate)))</p><p>This way you get a meaningful parameterised type that relates to array <a href="https://mastodon.sdf.org/tags/types" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>types</span></a></p><p>Edit: Scroll down to <span class="h-card"><a href="https://mastodon.tymoon.eu/@shinmera" class="u-url mention" rel="nofollow noopener noreferrer" target="_blank">@<span>shinmera</span></a></span>'s commentary</p>