104 lines
4.4 KiB
HTML
104 lines
4.4 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> Background and Getting Started</TITLE>
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</HEAD>
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<BODY>
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<meta name="description" value=" Background and Getting Started">
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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="node4.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="node2.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="node4.html"> Basic Data Types</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="node2.html"> LISt Processing</A>
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<BR> <HR> <P>
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<H1> Background and Getting Started</H1>
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<P>
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<em>LISP</em> is an acronym for <b> LIS</b>t <b> P</b>rocessor. It was developed by John
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McCarthy in the late 1950s, and his account of its history can be found at
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<a href="http://www-formal.stanford.edu/jmc/history/lisp/lisp.html" target="mccarthy">http://www-formal.stanford.edu/jmc/history/lisp/lisp.html</a>. Lisp found many adherents in the artificial
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intelligence community, and it is one of the oldest computer
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languages still in widespread use.
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<P>
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There are many variants (or dialects) of Lisp including Scheme, T,
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etc. In the 1980s there was an attempt to standardize the language.
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The result is Common Lisp (see Guy L. Steele, Jr., <em> Common Lisp: The
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Language, 2nd Edition</em>, Digital Press, 1990). Common Lisp is now the
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most popular dialect.
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<P>
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If you are familiar with another programming language, such as C,
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Pascal, or Fortran, you will be familiar with the concept of a
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compiler. A compiler is a program that takes a complete program
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written in one of these languages and turns it into a set of binary
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instructions that the computer can process. All major implemenations
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of Lisp provide a compiler, but unlike most languages, Lisp is also
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often used as an interpreted language. This means that you can start
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an interpreter which can process and respond directly to programs
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written in Lisp. Interacting with an interpreter makes easy
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interactive prototyping and debugging of programs possible. Once
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compiled, Lisp programs run just as fast and efficiently as
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well-written code in other standardly-compiled languages.
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<P>
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When you start up a Lisp interpreter, a prompt will appear, something like this:
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<P>
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<BLOCKQUOTE>
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<PRE>>
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</PRE>
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</BLOCKQUOTE>
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The Lisp interpreter waits for you to enter a well-formed Lisp
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expression. Once you have entered an expression, it immediately
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evaluates the expression entered and returns a response. For
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example:
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<P>
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<BLOCKQUOTE>
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<PRE>> (+ 1 2 3 4)
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10
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>
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</PRE>
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</BLOCKQUOTE>
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In this example, the user typed the Lisp expression (+ 1 2 3 4) and the interpreter responded with 10 and a new prompt.
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<P>
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The interpreter runs what is known as a <em> read-eval-print</em> loop. That
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is, it <em> reads</em> what you type, <em> evaluates</em> it, and then <em> prints</em> the result, before providing another prompt.
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<P>
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In what follows, it will be assumed that you have a Lisp interpreter
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running in front of you. Exactly how to start Lisp up will depend on
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the computer system you are using. If you need to, check the instructions for your Lisp interpreter or ask a local person to find out
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how to get started. You will also need to know how to get out of the
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Lisp interpreter. This too varies, even between implementations of
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Common Lisp, but (quit), (exit), and (bye) are some common alternatives.
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<P>
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Do not go any further until you know how to start up and exit
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Lisp on your system.
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<P>
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<BR> <HR>
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<A HREF="node4.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="node2.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="node4.html"> Basic Data Types</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="node2.html"> LISt Processing</A>
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<BR> <HR> <P>
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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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