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POJ : creating a family of verbs from an array
 

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    <p>The following expression shows a truth table for each of the 16 primitive Boolean operations:</p> <pre><code> (0 b./; 1 b./; 2 b./; 3 b./; 4 b./; 5 b./; 6 b./; 7 b./; 8 b./; 9 b./; 10 b./; 11 b./; 12 b./; 13 b./; 14 b./; 15 b./) ~ i.2 ┌───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┐ │0 0│0 0│0 0│0 0│0 1│0 1│0 1│0 1│1 0│1 0│1 0│1 0│1 1│1 1│1 1│1 1│ │0 0│0 1│1 0│1 1│0 0│0 1│1 0│1 1│0 0│0 1│1 0│1 1│0 0│0 1│1 0│1 1│ └───┴───┴───┴───┴───┴───┴───┴───┴───┴───┴───┴───┴───┴───┴───┴───┘ </code></pre> <p>How can I refactor the part in parentheses to remove the duplication?</p> <p><strong>clarification</strong>:</p> <p>The goal here isn't to produce the table, but rather to learn how to produce new verbs dynamically. In order to reduce the parenthesized expression, I would want to factor out the symbols <code>;</code> , <code>/</code> and <code>b.</code> , and then replace the numbers with <code>i.10</code>.</p> <p>The <code>;</code> symbol is easy enough:</p> <pre><code> ;/i.16 ┌─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬──┬──┬──┬──┬──┬──┐ │0│1│2│3│4│5│6│7│8│9│10│11│12│13│14│15│ └─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴──┴──┴──┴──┴──┴──┘ </code></pre> <p>But I'm having a hard time finding a way to produce a new verb from each element in the list.</p> <p>I think maybe I'm looking for some kind of higher-order combinators that allow using <code>&amp;</code> and <code>@</code> with something other than constants.</p> <p>For example, <code>nn leftBondEach v</code> might make an array of verbs equivalent to <code>n0 &amp; v; n1 &amp; v; ... ; nn &amp; v</code> :</p> <pre><code> bverbs =: (i.16)(leftBondEach)b. NB. would mean (0 b.; 1 b.; ...; 15 b.) 0 bverbs 0 ┌─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┐ │0│0│0│0│0│0│0│0│1│1│1│1│1│1│1│1│ └─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┘ 0 bverbs 1 ┌─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┐ │0│0│0│0│1│1│1│1│0│0│0│0│1│1│1│1│ └─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┘ </code></pre> <p>I think I need something similar in order to append the <code>/</code> to each function.</p> <p>Then again, this is J and there's probably a completely different way to approach these problems that I just haven't grokked yet. :)</p>
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