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88 lines
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<H2>Issue MACROEXPAND-HOOK-DEFAULT Writeup</H2>
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<PRE><B>Issue:</B> <A HREF="iss233.htm">MACROEXPAND-HOOK-DEFAULT</A><P>
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<B>Forum:</B> Editorial<P>
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<B>References:</B> <A REL=DEFINITION HREF="../Body/f_mexp_.htm#macroexpand"><B>MACROEXPAND</B></A> (pp151-152), <A REL=DEFINITION HREF="../Body/v_mexp_h.htm#STmacroexpand-hookST"><B>*MACROEXPAND-HOOK*</B></A> (p152)<P>
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<B>Category:</B> CLARIFICATION<P>
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<B>Edit history:</B> 02-Mar-91, Version 1 by Pitman<P>
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<B>Status:</B> For X3J13 consideration<P>
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<P>
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<B>Problem Description:<P>
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</B><P>
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In the description of the <A REL=DEFINITION HREF="../Body/f_mexp_.htm#macroexpand"><B>MACROEXPAND</B></A> function on p152 of CLtL,<P>
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it says ``The initial value of <A REL=DEFINITION HREF="../Body/v_mexp_h.htm#STmacroexpand-hookST"><B>*MACROEXPAND-HOOK*</B></A> is <A REL=DEFINITION HREF="../Body/f_funcal.htm#funcall"><B>FUNCALL</B></A>.''<P>
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<P>
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Does that mean the symbol <A REL=DEFINITION HREF="../Body/f_funcal.htm#funcall"><B>FUNCALL</B></A>, the function <A REL=DEFINITION HREF="../Body/f_funcal.htm#funcall"><B>FUNCALL</B></A>, or either?<P>
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<P>
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<B>Proposal (MACROEXPAND-HOOK-DEFAULT:EXPLICITLY-VAGUE):<P>
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</B><P>
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Specify that the initial value of <A REL=DEFINITION HREF="../Body/v_mexp_h.htm#STmacroexpand-hookST"><B>*MACROEXPAND-HOOK*</B></A> is either <P>
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the symbol <A REL=DEFINITION HREF="../Body/f_funcal.htm#funcall"><B>FUNCALL</B></A> or the function which it names.<P>
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<P>
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<B>Test Case:<P>
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</B><P>
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None.<P>
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<P>
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<B>Rationale:<P>
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</B><P>
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This leaves flexibility to an implementation which needs it to be<P>
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#'<A REL=DEFINITION HREF="../Body/f_funcal.htm#funcall"><B>FUNCALL</B></A> for speed. <P>
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<P>
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<B>Current Practice:<P>
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</B><P>
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In Symbolics Genera, the value is a function.<P>
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<P>
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<B>Cost to Implementors:<P>
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</B><P>
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None.<P>
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<P>
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<B>Cost to Users:<P>
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</B><P>
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None.<P>
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<P>
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<B>Cost of Non-Adoption:<P>
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</B><P>
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Lack of clear specification means mainly that implementors might worry<P>
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they were doing the wrong thing if they use #'<A REL=DEFINITION HREF="../Body/f_funcal.htm#funcall"><B>FUNCALL</B></A>, but might worry<P>
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about needless inefficiency if they use the symbol <A REL=DEFINITION HREF="../Body/f_funcal.htm#funcall"><B>FUNCALL</B></A> instead.<P>
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<P>
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<B>Benefits:<P>
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</B><P>
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Clearer specification.<P>
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<P>
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<B>Aesthetics:<P>
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</B><P>
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Negligible.<P>
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<P>
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<B>Discussion:<P>
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</B><P>
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Pitman doesn't care which way this is decided.<P>
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</PRE>
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