<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "> <br>I almost always perform tests with eq? or equal?, seldom (if ever) with eqv? . The Reference is a bit mysterious, saying (in section 3.1)<div><br></div><div><p style="margin: 0.0px 0.0px 16.0px 0.0px"><font face="Times" size="5" style="font: 16.0px Times">Two values are <a href="file:///Applications/PLT%20Scheme%20Full%20v4.1.0.3/doc/reference/booleans.html#(def._((quote._~23~25kernel)._eqv~3f))"><font face="Courier" size="4" color="#0022f2" style="font: 13.0px Courier; color: #0022f2">eqv?</font></a> if and only if they are <a href="file:///Applications/PLT%20Scheme%20Full%20v4.1.0.3/doc/reference/booleans.html#(def._((quote._~23~25kernel)._eq~3f))"><font face="Courier" size="4" color="#0022f2" style="font: 13.0px Courier; color: #0022f2">eq?</font></a>, unless otherwise specified for a particular datatype.</font></p><div> <span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div>That doesn't help much. Well, it <i>does</i> help, but only by telling me that they are usually the same. Heuristically, I think of eq? as being similar to comparing pointers in C and equal? as a test that might involve library call that could run in time proportional to the size of the objects (e.g., strcmp). What is the intuition behind eqv?<br class="Apple-interchange-newline"><br class="khtml-block-placeholder"></div><div>"In the human mind, one-sidedness has </div><div>always been the rule and many-sidedness the</div><div> exception. Hence, even in revolutions of </div><div>thought, one part of the truth usually sets while</div><div> another rises."</div><div>--John Stuart Mill</div><div><br></div><div><div><a href="http://www.gwoodhouse.com">http://www.gwoodhouse.com</a></div><div><a href="http://GregWoodhouse.ImageKind.com">http://GregWoodhouse.ImageKind.com</a></div><div><br></div></div><div><br class="khtml-block-placeholder"></div><br class="Apple-interchange-newline"></span><br class="Apple-interchange-newline"></span> </div><br></div></body></html>