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35 lines
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<TITLE>CLHS: Section 25.1.1</TITLE>
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25.1.1 Top level loop</H2> The top level loop is the Common Lisp mechanism by which the user normally interacts with the Common Lisp system. This loop is sometimes referred to as the <A REL=DEFINITION HREF="26_glo_l.htm#lisp_read-eval-print_loop"><I>Lisp read-eval-print loop</I></A> because it typically consists of an endless loop that reads an expression, evaluates it and prints the results. <P>
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The top level loop is not completely specified; thus the user interface is <A REL=DEFINITION HREF="26_glo_i.htm#implementation-defined"><I>implementation-defined</I></A>. The top level loop prints all values resulting from the evaluation of a <A REL=DEFINITION HREF="26_glo_f.htm#form"><I>form</I></A>. The next figure lists variables that are maintained by the <A REL=DEFINITION HREF="26_glo_l.htm#lisp_read-eval-print_loop"><I>Lisp read-eval-print loop</I></A>. <P>
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<A REL=DEFINITION HREF="a_st.htm#ST">*</A> <A REL=DEFINITION HREF="a_pl.htm#PL">+</A> <A REL=DEFINITION HREF="a_sl.htm#SL">/</A> <A REL=DEFINITION HREF="a__.htm#-">-</A>
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<A REL=DEFINITION HREF="v__stst_.htm#STST">**</A> <A REL=DEFINITION HREF="v_pl_plp.htm#PLPL">++</A> <A REL=DEFINITION HREF="v_sl_sls.htm#SLSL">//</A>
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<A REL=DEFINITION HREF="v__stst_.htm#STSTST">***</A> <A REL=DEFINITION HREF="v_pl_plp.htm#PLPLPL">+++</A> <A REL=DEFINITION HREF="v_sl_sls.htm#SLSLSL">///</A>
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<P><B>Figure 25-1. Variables maintained by the Read-Eval-Print Loop</B> <P>
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