64 lines
1.8 KiB
HTML
64 lines
1.8 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> Lambda Expressions</TITLE>
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</HEAD>
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<BODY>
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<meta name="description" value=" Lambda Expressions">
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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="node67.html"><IMG ALIGN=BOTTOM ALT="next" SRC="next_motif.gif"></A>
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<A HREF="node64.html"><IMG ALIGN=BOTTOM ALT="up" SRC="up_motif.gif"></A>
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<A HREF="node65.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="node67.html"> Funcall</A>
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<B>Up:</B>
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<A HREF="node64.html"> FunctionsLambda Expressions, </A>
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<B> Previous:</B>
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<A HREF="node65.html"> Eval</A>
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<BR> <HR> <P>
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<H1> Lambda Expressions</H1>
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The Lambda Expression is the heart of Lisp's notion of a function.
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The term comes from Alonzo Church's ``lambda calculus'' -- a
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development of mathematical logic. You can think of a lambda
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expression as an anonymous function. Just like a function it has a
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list of parameters and a block of code specifying operations on those
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parameters.
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<p>
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For example:
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<pre>
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> (setf product '(lambda (x y) (* x y)))
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(LAMBDA (X Y) (* X Y))
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> product
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(LAMBDA (X Y) (* X Y))
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</pre>
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Note that in some recent versions of Common Lisp, the lambda
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expression should be unquoted, or the next step will not work.
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<br>Use <tt>(setf product (lambda (x y) (* x y)))</tt> instead.
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<p>
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Lambda expressions can be used in conjunction with <a
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href="node68.html">apply</a> to mimic function calls:
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<pre>
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> (apply product '(3 4))
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12
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</pre>
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<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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