79 lines
2.2 KiB
HTML
79 lines
2.2 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3O//DTD W3 HTML 2.0//EN">
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<!Originally converted to HTML using LaTeX2HTML 95 (Thu Jan 19 1995) by Nikos Drakos (nikos@cbl.leeds.ac.uk), CBLU, University of Leeds >
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<HEAD>
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<TITLE> Basic Data Types</TITLE>
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</HEAD>
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<BODY>
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<meta name="description" value=" Basic Data Types">
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<meta name="keywords" value="lp">
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<meta name="resource-type" value="document">
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<meta name="distribution" value="global">
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<P>
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<BR> <HR>
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<A HREF="node5.html"><IMG ALIGN=BOTTOM ALT="next" SRC="next_motif.gif"></A>
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<A HREF="node2.html"><IMG ALIGN=BOTTOM ALT="up" SRC="up_motif.gif"></A>
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<A HREF="node3.html"><IMG ALIGN=BOTTOM ALT="previous" SRC="previous_motif.gif"></A> <BR>
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<A HREF="lp.html"><B>Contents</B></A>
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<B> Next:</B>
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<A HREF="node5.html"> Atoms</A>
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<B>Up:</B>
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<A HREF="node2.html"> LISt Processing</A>
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<B> Previous:</B>
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<A HREF="node3.html"> Background and Getting </A>
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<BR> <HR> <P>
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<H1> Basic Data Types</H1>
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<P>
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The two most important kinds of objects in Lisp for you to know about
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are atoms and lists. These two kinds are mutually exclusive, with the
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exception of one special entity, the empty list, known as ``()'' or
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``nil,'' which is both an atom and a list. Atoms include symbols,
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arrays, and various other data structures. For beginning purposes,
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we'll restrict our attention to the subset of atoms that are
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<em>symbols</em>.
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<P>
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Symbols are represented as sequences of characters of reasonable length.
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<P>
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Lists are recursively constructed from atoms. This means that a
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given list may contain either atoms or other lists as members.
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<P>
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Examples:
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<P>
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<BLOCKQUOTE>
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<PRE><TT>
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SYMBOLS LISTS
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<P>
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a ()
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<P>
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john (a)
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<P>
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34 (a john 34 c3po)
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<P>
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c3po ((john 34) a ((c3po)))
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<P>
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</TT></PRE>
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</BLOCKQUOTE>
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<P>
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<P>
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Symbols and lists are both legal Lisp expressions for the interpreter
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to read and evaluate. The rules for evaluating symbols and lists in
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Lisp are very simple (one of the great beauties of the language).
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They are covered in the next two sections.
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<P>
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<BR> <HR>
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<UL>
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<LI>
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<A HREF="node5.html"> Atoms</A>
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<LI>
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<A HREF="node6.html"> Lists</A>
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</UL>
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<BR> <HR>
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<P>
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<ADDRESS>
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<I>© Colin Allen & Maneesh Dhagat <BR>
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March 2007 </I>
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</ADDRESS>
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</BODY>
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