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-95 core.logic <p>This snippet wrongly succeeds with the result: <div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent"> <pre class="code-java">(([foo _0] :- (!= (foo _0))))</pre> </div></div></p> <div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent"> <pre class="code-java">(run* [q] (nom/fresh [a b] (fresh [x y] (!= x y) (== (nom/tie a (nom/tie b [b y])) (nom/tie b (nom/tie a [a x]))) (== x 'foo) (== [x y] q))))</pre> </div></div> <p>Moving the disequality anywhere further down makes the snippet rightly fail.</p> LOGIC-95

disequality

Defect Blocker Resolved Completed David Nolen Nada Amin Fri, 4 Jan 2013 05:16:39 -0600 Fri, 4 Jan 2013 11:23:47 -0600 Fri, 4 Jan 2013 11:23:47 -0600 0 0 <p>An insight: if I remove the -relevant-var? protocol from !=c in core.logic, then this works and all other tests pass. Of course, this probably has performance applications, so thinking of alternatives.</p> <p>The problem is not specific to nominal disequality. Here is the same bug with only core.logic:</p> <div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent"> <pre class="code-java">(run* [q] (fresh [x y w z] (!= x y) (!= w z) (== z y) (== x 'foo) (== y 'foo)))</pre> </div></div> <p>This should fail, because x == y == 'foo, but instead we get: <div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent"> <pre class="code-java">(_0 :- (!= (_1 foo)) (!= (foo foo))))</pre> </div></div>.</p> <p>The problem is that var-rands takes the substitution map into account, while -relevant-var doesn't.</p> <p>Another way disequality is broken:</p> <div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent"> <pre class="code-java">(run* [q] (fresh [x y w z] (!= x [y]) (== x ['foo]) (== y 'foo)))</pre> </div></div> <p>This snippet should fail, but instead returns '(_0). This is because y is not returned by recover-vars.</p> <p>diseq.diff contains detailed commit message explaining the issues, fixes, and tests.</p> <p>fixed, <a href="http://github.com/clojure/core.logic/commit/fb489298417c643fdd03efbf6951e998e6821910">http://github.com/clojure/core.logic/commit/fb489298417c643fdd03efbf6951e998e6821910</a></p> Global Rank