<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><br></div><div><blockquote type="cite"><div><font class="Apple-style-span" color="#000000">Welcome to DrRacket, version 5.0.99.2--2010-11-11(686ec83/g) [3m].</font></div><div><font class="Apple-style-span" color="#000000">Language: Beginning Student.</font></div><div><font class="Apple-style-span" color="#000000">> (member? 1 (list 2 3 4 1))</font></div><div><font class="Apple-style-span" color="#000000">true</font></div></blockquote><br></div><div><br></div><div><br></div><br><div><div>On Nov 11, 2010, at 10:32 AM, Shriram Krishnamurthi wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><p>In fact, I proposed adding the ? forms of these functions where the new ones are strictly boolean. </p><p>These are essential for the SLs since the standard versions are useless due to the true/false tests in the language. </p><div><br class="webkit-block-placeholder"></div><blockquote type="cite">On Nov 11, 2010 6:44 AM, "Jay McCarthy" <<a href="mailto:jay.mccarthy@gmail.com">jay.mccarthy@gmail.com</a>> wrote:<br><br>I agree with Mark. I often write ? versions of functions like member<br> in my code when I write it the first time to show the "predicate<br> intent".<br> <br> Another important case is when you don't want internal values to<br> "escape" to the client because you forget that member/and/etc return<br> the thing, not #t.<br> <br> Jay<br><p><font color="#500050"><br>On Thu, Nov 11, 2010 at 6:07 AM, Sam Tobin-Hochstadt <<a href="mailto:samth@ccs.neu.edu">samth@ccs.neu.edu</a>> wrote:<br>> On Thu, Nov 11, 2...</font></p><font color="#888888">--<br> Jay McCarthy <<a href="mailto:jay@cs.byu.edu">jay@cs.byu.edu</a>><br> Assistant Professor / Brigham Young University<br> <a href="http://faculty.cs.byu.edu/~jay" target="_blank">http://faculty.cs.byu.edu/~jay</a><br> <br> "The glory of God is Intelligence" - D&C 93<br> </font><p><font color="#500050">_________________________________________________<br> For list-related administrative tasks:<br> <a href="http://...">http://...</a></font></p></blockquote><div><br class="webkit-block-placeholder"></div> _________________________________________________<br>  For list-related administrative tasks:<br>  <a href="http://lists.racket-lang.org/listinfo/users">http://lists.racket-lang.org/listinfo/users</a></blockquote></div><br></body></html>