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POHow to handle specific case Java variable length arguments in Clojure?
 

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  1. POHow to handle specific case Java variable length arguments in Clojure?
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    <p>I'm trying to port some Java code to Clojure and I ran into a situation that I can't solve.</p> <p>Normally when you want call a Java constructor or method with a variable length argument you do something like this</p> <pre><code>(Fields. (into-array Comparable ["predict", "other"])) </code></pre> <p>However I found a special example where this doesn't work:</p> <pre><code>(Fields. (into-array Comparable ["predict", Double])) </code></pre> <p>Although this seems possible in Java (see below), the code above gives the following error:</p> <pre><code>IllegalArgumentException array element type mismatch java.lang.reflect.Array.set (Array.java:-2) </code></pre> <p>I tried a couple of variations, but nothing seems to work. The Java code I try to port (and the specific line that gives trouble) is here <a href="https://github.com/Cascading/pattern/blob/wip-1.0/pattern-examples/src/main/java/cascading/pattern/Main.java#L76" rel="nofollow">https://github.com/Cascading/pattern/blob/wip-1.0/pattern-examples/src/main/java/cascading/pattern/Main.java#L76</a></p> <pre><code>new Fields( "predict", Double.class ) </code></pre> <p>(The constructor signature for Fields is Fields(Comparable... fields) <a href="http://docs.cascading.org/cascading/2.1/javadoc/cascading/tuple/Fields.html#Fields(java.lang.Comparable...)" rel="nofollow">http://docs.cascading.org/cascading/2.1/javadoc/cascading/tuple/Fields.html#Fields(java.lang.Comparable...)</a></p> <p>I tried the following examples in the Clojure repl:</p> <pre><code>(into-array Comparable [(type Double)]) (into-array Comparable [Double/TYPE]) (into-array Comparable [Double]) =&gt; IllegalArgumentException array element type mismatch java.lang.reflect.Array.set (Array.java:-2) </code></pre>
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    1. USJeroen van Dijk
    1. USJeroen van Dijk
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    1. COWhich variations? In the Java case the 2nd parameter is a *class*. I'm not fluent in Clojure, have you tried something like Double.class, Double.type, (class Double), (type Double)?
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    2. COI'm puzzled as to why this works in Java. Double.class should be of type Class, which does not implement Comparable. Unfortunately I don't have a Java compiler at hand to check that.
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      1. USRafał Dowgird
    3. CO@Berrylium Yeah basically those. Thanks I updated the question.
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      1. USJeroen van Dijk
 

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