https://ask.clojure.org/index.php/tag/isa%3F https://ask.clojure.org/index.php/9205/how-to-check-whether-an-object-is-of-a-certain-type <p>Looking at the documentation for <a rel="nofollow" href="https://clojuredocs.org/clojure.core/type">type</a> I see how to find a type of an object. And in the see-also section it talks about the function <code>instance?</code> which tests whether an object is a member of a designated class. </p> <p>Is the documentation using the word class and type interchangeably here?<br> What is the correct way to check type membership, assuming I have a type designator compatible with <code>isa?</code> ?</p> Records and Types https://ask.clojure.org/index.php/9205/how-to-check-whether-an-object-is-of-a-certain-type Wed, 01 Apr 2020 09:10:09 +0000 https://ask.clojure.org/index.php/9204/generalizing-isa <p>I'm trying to understand how to use the <code>isa?</code> function, but I don't yet understand exactly what the valid arguments of this function are, but somehow they are type-designators, or type-names, or whatever the clojure terminology for that is.<br> My question is: given two valid type-designators for <code>isa?</code> how do I find out whether the two designated types intersect. I.e., is it possible to have an object which is of both types?</p> <p>The <a rel="nofollow" href="https://blog.ambrosebs.com/2020/03/30/what-type-clojure.html">blog post of Ambrose</a> sort of hints at this enough to make me even more curious.<br> As the blog post specifies, there is no equivalent of the Common Lisp <code>subtypep</code> function in clojure. But in Common Lisp I can ask whether type A is a subtype of B, and I can express intersection types as (and A B). Thus I can ask intersection questions by asking whether the intersection is a subtype of the empty type. <code>(subtypep (and A B) nil)</code></p> <p>What is the closest to that that exists in clojure?</p> Records and Types https://ask.clojure.org/index.php/9204/generalizing-isa Wed, 01 Apr 2020 07:35:02 +0000