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<div><br></div><div><br></div><div>The TLS is plain old wrong. Take it from its author/co. </div><div><br></div><div>* When Dan wrote TLL(1), people had just scratched the surface of semantics. Dan wrote down what people saw and whenever he wrote "what is the value of", he meant "what does a conventional Lisp/Scheme interpreter print when you type this into its repl." </div><div><br></div><div>* I left it alone because Dan wanted a light-hearted introduction to "heavy" topics. Changing that would have pushed it way far away from "sit down with an interpreter and play" atmosphere. </div><div><br></div><div>* For a semanticist, however, all of this is nonsense. A syntactic way of "doing semantics" is to find some SUBSET of the language of expressions that represents "things that we no longer have to calculate with because the answer is obvious" aka VALUES, and to come up with relations that map programs to elements of this set. In this spirit, (a b c) is by no means a value. It is an expression that applies a to the arguments b and c. On the other hand '(a b c) IS an expression, it IS obvious what it means, and so it IS natural to think of it as a value, though I tend to think of it as a short-hand for a value. </div><div><br></div><div>A model-oriented way of "doing semantics" would certainly represent '(a b c) as some 'object that stores three symbols.' (Whatever the object is: a record in some language, an element of a tuple space in the Scott-domain world.) Again, there is NO WAY to equate this object with (a b c), which would denote the result of an application. </div><div><br></div><div>So enough said. I am tuning out. -- Matthias</div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><br><div><div>On Oct 19, 2008, at 10:02 PM, Woodhouse Gregory wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"> Don't you think the problem ultimately comes down to the limits of natural language? After all, the question was posed in English. In "The Little Schemer" there is a chapter (9?) where a great deal of emphasis is placed on the differing typefaces used (in that book) for atoms and bits of Scheme code. By introducing this convention, TLS is, in effect, using an artificial language to circumvent some of the difficulties of ordinary English (even as used to discuss languages like Scheme).<div><br></div><div>I would have answered (a b c), but I appreciate the arguments for using '(a b c) and, to me, it seems that both are a kind of compromise.<br><div><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><br class="Apple-interchange-newline"><br class="khtml-block-placeholder"></div><div>"Interaction is the mind-body problem</div><div>of computing." --Philip L. Wadler</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><div><br class="khtml-block-placeholder"></div><br class="Apple-interchange-newline"></span><br class="Apple-interchange-newline"></span> </div><br><div><div>On Oct 19, 2008, at 2:45 PM, Shriram Krishnamurthi wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: 12.0px Helvetica">On Sun, Oct 19, 2008 at 4:31 PM, Richard Cleis <<a href="mailto:rcleis@me.com">rcleis@me.com</a>> wrote:</font></div> <blockquote type="cite"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 10px; "><font face="Helvetica" size="3" style="font: 12.0px Helvetica">Does the following progression make sense, by ordinary standards of</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 10px; "><font face="Helvetica" size="3" style="font: 12.0px Helvetica">Ameringlish?</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 10px; font: normal normal normal 12px/normal Helvetica; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 10px; "><font face="Helvetica" size="3" style="font: 12.0px Helvetica">(car '((a b c) x y z)) is '(a b c)</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 10px; font: normal normal normal 12px/normal Helvetica; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 10px; "><font face="Helvetica" size="3" style="font: 12.0px Helvetica">The value of (car '((a b c) x y z)) is (a b c)</font></div> </blockquote><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Helvetica; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: 12.0px Helvetica">Not to me.</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Helvetica; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: 12.0px Helvetica"><span class="Apple-converted-space"> </span>(a b c)</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Helvetica; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: 12.0px Helvetica">is an expression, not a value.<span class="Apple-converted-space"> </span>It may also be the print</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: 12.0px Helvetica">representation chosen by some particular implementation for some</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: 12.0px Helvetica">particular value, but then so is</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Helvetica; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: 12.0px Helvetica"><span class="Apple-converted-space"> </span>/---+---+---\</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: 12.0px Helvetica"><span class="Apple-converted-space"> </span>| a | b | c |</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: 12.0px Helvetica"><span class="Apple-converted-space"> </span>\---+---+---/</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Helvetica; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: 12.0px Helvetica">(Do you see my point?)</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Helvetica; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: 12.0px Helvetica">Shriram</font></div> </blockquote></div><br></div></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; 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