101 lines
8.7 KiB
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101 lines
8.7 KiB
HTML
<!-- Common Lisp HyperSpec (TM), version 7.0 generated by Kent M. Pitman on Mon, 11-Apr-2005 2:31am EDT -->
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<TITLE>CLHS: Function FUNCTION-LAMBDA-EXPRESSION</TITLE>
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<H1><A REV=MADE HREF="http://www.lispworks.com/"><IMG WIDTH=80 HEIGHT=65 ALT="[LISPWORKS]" SRC="../Graphics/LWSmall.gif" ALIGN=Bottom></A><A REL=TOP HREF="../Front/index.htm"><IMG WIDTH=237 HEIGHT=65 ALT="[Common Lisp HyperSpec (TM)]" SRC="../Graphics/CLHS_Sm.gif" ALIGN=Bottom></A> <A REL=PREV HREF="s_fn.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Previous]" SRC="../Graphics/Prev.gif" ALIGN=Bottom></A><A REL=UP HREF="c_data_a.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Up]" SRC="../Graphics/Up.gif" ALIGN=Bottom></A><A REL=NEXT HREF="f_fnp.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Next]" SRC="../Graphics/Next.gif" ALIGN=Bottom></A></H1>
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<A NAME="function-lambda-expression"><I>Function</I> <B>FUNCTION-LAMBDA-EXPRESSION</B></A> <P>
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<P>
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<P><B>Syntax:</B><P>
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<P>
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<B>function-lambda-expression</B> <I>function</I><P> => <I>lambda-expression, closure-p, name</I><P>
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<P>
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<P><B>Arguments and Values:</B><P>
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<P>
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<I>function</I>---a <A REL=DEFINITION HREF="26_glo_f.htm#function"><I>function</I></A>. <P>
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<I>lambda-expression</I>---a <A REL=DEFINITION HREF="26_glo_l.htm#lambda_expression"><I>lambda expression</I></A> or <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A>. <P>
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<I>closure-p</I>---a <A REL=DEFINITION HREF="26_glo_g.htm#generalized_boolean"><I>generalized boolean</I></A>. <P>
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<I>name</I>---an <A REL=DEFINITION HREF="26_glo_o.htm#object"><I>object</I></A>. <P>
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<P><B>Description:</B><P>
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<P>
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Returns information about <I>function</I> as follows: <P>
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The <A REL=DEFINITION HREF="26_glo_p.htm#primary_value"><I>primary value</I></A>, <I>lambda-expression</I>, is <I>function</I>'s defining <A REL=DEFINITION HREF="26_glo_l.htm#lambda_expression"><I>lambda expression</I></A>, or <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A> if the information is not available. The <A REL=DEFINITION HREF="26_glo_l.htm#lambda_expression"><I>lambda expression</I></A> may have been pre-processed in some ways, but it should remain a suitable argument to <A REL=DEFINITION HREF="f_cmp.htm#compile"><B>compile</B></A> or <A REL=DEFINITION HREF="s_fn.htm#function"><B>function</B></A>. Any <A REL=DEFINITION HREF="26_glo_i.htm#implementation"><I>implementation</I></A> may legitimately return <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A> as the <I>lambda-expression</I> of any <I>function</I>. <P>
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The <A REL=DEFINITION HREF="26_glo_s.htm#secondary_value"><I>secondary value</I></A>, <I>closure-p</I>, is <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A> if <I>function</I>'s definition was enclosed in the <A REL=DEFINITION HREF="26_glo_n.htm#null_lexical_environment"><I>null lexical environment</I></A> or something <A REL=DEFINITION HREF="26_glo_n.htm#non-nil"><I>non-nil</I></A> if <I>function</I>'s definition might have been enclosed in some <A REL=DEFINITION HREF="26_glo_n.htm#non-null_lexical_environment"><I>non-null lexical environment</I></A>. Any <A REL=DEFINITION HREF="26_glo_i.htm#implementation"><I>implementation</I></A> may legitimately return <A REL=DEFINITION HREF="26_glo_t.htm#true"><I>true</I></A> as the <I>closure-p</I> of any <I>function</I>. <P>
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The <A REL=DEFINITION HREF="26_glo_t.htm#tertiary_value"><I>tertiary value</I></A>, <I>name</I>, is the ``name'' of <I>function</I>. The name is intended for debugging only and is not necessarily one that would be valid for use as a name in <A REL=DEFINITION HREF="m_defun.htm#defun"><B>defun</B></A> or <A REL=DEFINITION HREF="s_fn.htm#function"><B>function</B></A>, for example. By convention, <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A> is used to mean that <I>function</I> has no name. Any <A REL=DEFINITION HREF="26_glo_i.htm#implementation"><I>implementation</I></A> may legitimately return <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A> as the <I>name</I> of any <I>function</I>. <P>
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<P><B>Examples:</B><P>
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<P>
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The following examples illustrate some possible return values, but are not intended to be exhaustive: <P>
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<PRE>
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(function-lambda-expression #'(lambda (x) x))
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=> NIL, <A REL=DEFINITION HREF="26_glo_f.htm#false">false</A>, NIL
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OR=> NIL, <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>, NIL
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OR=> (LAMBDA (X) X), <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>, NIL
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OR=> (LAMBDA (X) X), <A REL=DEFINITION HREF="26_glo_f.htm#false">false</A>, NIL
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(function-lambda-expression
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(funcall #'(lambda () #'(lambda (x) x))))
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=> NIL, <A REL=DEFINITION HREF="26_glo_f.htm#false">false</A>, NIL
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OR=> NIL, <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>, NIL
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OR=> (LAMBDA (X) X), <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>, NIL
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OR=> (LAMBDA (X) X), <A REL=DEFINITION HREF="26_glo_f.htm#false">false</A>, NIL
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(function-lambda-expression
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(funcall #'(lambda (x) #'(lambda () x)) nil))
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=> NIL, <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>, NIL
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OR=> (LAMBDA () X), <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>, NIL
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NOT=> NIL, <A REL=DEFINITION HREF="26_glo_f.htm#false">false</A>, NIL
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NOT=> (LAMBDA () X), <A REL=DEFINITION HREF="26_glo_f.htm#false">false</A>, NIL
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(flet ((foo (x) x))
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(setf (symbol-function 'bar) #'foo)
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(function-lambda-expression #'bar))
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=> NIL, <A REL=DEFINITION HREF="26_glo_f.htm#false">false</A>, NIL
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OR=> NIL, <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>, NIL
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OR=> (LAMBDA (X) (BLOCK FOO X)), <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>, NIL
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OR=> (LAMBDA (X) (BLOCK FOO X)), <A REL=DEFINITION HREF="26_glo_f.htm#false">false</A>, FOO
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OR=> (SI::BLOCK-LAMBDA FOO (X) X), <A REL=DEFINITION HREF="26_glo_f.htm#false">false</A>, FOO
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(defun foo ()
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(flet ((bar (x) x))
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#'bar))
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(function-lambda-expression (foo))
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=> NIL, <A REL=DEFINITION HREF="26_glo_f.htm#false">false</A>, NIL
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OR=> NIL, <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>, NIL
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OR=> (LAMBDA (X) (BLOCK BAR X)), <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>, NIL
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OR=> (LAMBDA (X) (BLOCK BAR X)), <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>, (:INTERNAL FOO 0 BAR)
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OR=> (LAMBDA (X) (BLOCK BAR X)), <A REL=DEFINITION HREF="26_glo_f.htm#false">false</A>, "BAR in FOO"
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</PRE>
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</TT> <P>
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<P><B>Side Effects:</B> None.
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<P>
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<P><B>Affected By:</B> None.
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<P>
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<P><B>Exceptional Situations:</B> None.
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<P>
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<P><B>See Also:</B> None.
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<P>
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<P><B>Notes:</B><P>
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<P>
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Although <A REL=DEFINITION HREF="26_glo_i.htm#implementation"><I>implementations</I></A> are free to return ``<A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A>, <A REL=DEFINITION HREF="26_glo_t.htm#true"><I>true</I></A>, <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A>'' in all cases, they are encouraged to return a <A REL=DEFINITION HREF="26_glo_l.htm#lambda_expression"><I>lambda expression</I></A> as the <A REL=DEFINITION HREF="26_glo_p.htm#primary_value"><I>primary value</I></A> in the case where the argument was created by a call to <A REL=DEFINITION HREF="f_cmp.htm#compile"><B>compile</B></A> or <A REL=DEFINITION HREF="f_eval.htm#eval"><B>eval</B></A> (as opposed to being created by <I>loading</I> a <A REL=DEFINITION HREF="26_glo_c.htm#compiled_file"><I>compiled file</I></A>). <P>
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<P>
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<P><HR>The following <A REL=META HREF="../Front/X3J13Iss.htm">X3J13 cleanup issue</A>, <I>not part of the specification</I>, applies to this section:<P><UL><LI> <A REL=CHILD HREF="../Issues/iss173.htm">FUNCTION-DEFINITION:JAN89-X3J13</A><P></UL><HR>
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