http://dev.clojure.org/jira This file is an XML representation of an issue en-us 4.4 649 25-07-2011 http://dev.clojure.org/jira/browse/LOGIC-102 core.logic <p>The second nom/hash throws an exception, because the nom/hash constraint is ran before the predc one.</p> <div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent"> <pre class="code-java">(is (= (run* [q] (nom/fresh [x] (fresh [y] (predc y nom? `nom?) (nom/hash y x) (== y 'foo)))) ())) (is (= (run* [q] (nom/fresh [x] (fresh [y] (nom/hash y x) (predc y nom? `nom?) (== y 'foo)))) ()))</pre> </div></div> <p>Perhaps, we can generalize the notion of hash.</p> LOGIC-102

generalize the notion of hash for robustness

Defect Major Resolved Completed David Nolen Nada Amin Mon, 7 Jan 2013 09:47:24 -0600 Mon, 11 Mar 2013 12:30:03 -0500 Mon, 7 Jan 2013 19:06:02 -0600 0 1 <p>Hmm but why throw in nom/hash like that instead of just failing?</p> <p>Closed wrong ticket</p> <p>ok, seems reasonable to fail.</p> <p>The fix to logic-101 is not entirely satisfactory, because we can now get constraints like _1#<span class="error">&#91;_1&#93;</span>. so i think i also want to not use predc (but still use fixc), but have a custom constraint instead of the predc that takes the two rands into account.</p> <p>implementing this now.</p> <p>The patch logic-102.diff gives up on predc and fixc, and instead does a lot of ugly special-casing to cover the new TDD test cases.</p> <p>Not too happy about this change...</p> <p>Is there something we could do to make it easier to rely on `fixc` and `predc`? Or is there some lacking feature of constraints?</p> <p>Also if you're OK w/ this patch, more than happy to move forward w/ this for now and it can be improved later.</p> <p>OK, as discussed, please go ahead with the patch, and I'll think of some alternatives / refactoring soon.</p> <p>fixed, <a href="http://github.com/clojure/core.logic/commit/417246ad0d854f9f82ae3b5aeb566ea00249eb2c">http://github.com/clojure/core.logic/commit/417246ad0d854f9f82ae3b5aeb566ea00249eb2c</a></p> <p>refactoring.diff refactors the logic a bit. Hopefully it's more readable.</p> <p>For now, it seems too much trouble for the gain to generalize hash or try to write it using more primitive constraints.</p> <p>Makes sense will apply later today.</p> <p>I am going to apply the refactoring to master. <img class="emoticon" src="http://dev.clojure.org/jira/images/icons/emoticons/smile.gif" height="20" width="20" align="absmiddle" alt="" border="0"/></p> <p>Applied in <a href="https://github.com/clojure/core.logic/commit/43d325bd8e3770f3483cc8be7d332adfae3a6a96">https://github.com/clojure/core.logic/commit/43d325bd8e3770f3483cc8be7d332adfae3a6a96</a></p> Global Rank