\edef\defun{\the\catcode`@}%
\catcode`@ = 11
\let\@oldatcatcode = \defun

\edef\defun{\the\catcode`&}%
\catcode`& = 11
\let\@oldandcatcode = \defun

\def\empty{\t{()}}
\def\false{\t{nil}}
\def\true{\t{t}}
\def\nil{\t{nil}}
\def\FALSE{\t{nil}}
\def\TRUE{\t{t}}
\def\NIL{\t{nil}}

\def\dlbrack{\lbrack\mskip-\thinmuskip\lbrack\mskip\thinmuskip}
\def\drbrack{\mskip\thinmuskip\rbrack\mskip-\thinmuskip\rbrack}

\def\mopt#1{{$\,\lbrack$}{\it #1\/}{$\rbrack\,$}}%
\def\mchoice#1{{$\,\dlbrack$}{\it #1\/}{$\drbrack\,$}}%
\def\mstar#1{{$\,\lbrace$}{\it #1\/}{$\rbrace^*\,$}}%
\def\mplus#1{{$\,\lbrace$}{\it #1\/}{$\rbrace^+\,$}}%
\def\mgroup#1{{$\,\lbrace$}{\it #1\/}{$\rbrace\,$}}%
\def\mor{{$|$}}%
\def\mind#1{$\downarrow${\it #1\/}}%

%% FUNCTIONS

{\catcode`&=11
 \def\&optional{\t{\& optional}}
 \def\&rest{\t{\& rest}}
 \def\&key{\t{\& key}}
}

\def\defun@vspace{\ifhmode\unskip \par\fi\addvspace{18pt plus 12pt minus 6pt}}
\def\defun@hspace{\ifhmode\unskip \par\fi\hskip1.5em}

% name and arguments are required 
% In between can be an optional package
\def\defun{\defun@vspace\defunx}
\def\defunx{\@defn{Function}}
\def\defn{\defun@vspace\@defn}
\def\defnx{\@defn}
\def\enddefun{\enddfn}
\def\enddefn{\enddfn}
\def\enddfn{\relax}

\def\@defunstart{\noindent\leavevmode     % Need this to trigger the \everypar for margin rules.
  \begingroup \samepage \raggedright
  \hyphenpenalty=-5  \exhyphenpenalty=\@M  \brokenpenalty=\@M}

\def\@defunend{\par\endgroup}

\def\above@defun{\@defunstart}
\def\below@defun{\@defunend\nobreak\addvspace{2pt plus 2pt minus 2pt}}

\def\@defn#1#2{\outer\def\defun@type{#1}\outer\def\defun@name{#2}%
\fnindexbold{#2}%
\@ifnextchar[{\@defunpackage}{\@defunnopackage}
}

\def\@defunpackage[#1]{%
\setbox0\hbox{\defun@hspace$\lbrack$\it\defun@type\/$\rbrack$}\relax
\setbox1\hbox{\tt#1:\defun@name\defun@hspace}\relax
\@defun
}

\def\@defunnopackage{%
\setbox0\hbox{\defun@hspace$\lbrack$\it\defun@type\/$\rbrack$}\relax
\setbox1\hbox{\tt\defun@name\defun@hspace}\relax
\@defun
}

\def\@defun#1{
\above@defun
\setbox2\hbox{\hskip\textwidth\hskip-1\wd0\hskip-1\wd1}\relax
\def\args##1{##1}%
\def\keys##1{{\tt \& key} \@settab {\tt ##1}}%
\def\morekeys##1{\@stopline\@startline\>{\tt\ignorespaces ##1}}%
\def\yetmorekeys##1{\@stopline\@startline\>{\tt\ignorespaces ##1}}%
\leavevmode\hbox to 0pt{\hbox 
	to \textwidth{\hss\box0}\hss}{\box1\begin{minipage}[t]{1\wd2}
		\begin{tabbing}
#1\end{tabbing}\end{minipage}}
\below@defun
}


%% MACROS

\def\defmac{\defun@vspace\defmacx}
\def\defmacx{\@defmc{Macro}}
\def\defspec{\defun@vspace\defspecx}
\def\defspecx{\@defmc{Special Form}}
\def\enddefspec{\enddfn}
\def\enddefmac{\enddfn}

\def\@defmc#1#2{\outer\def\defun@type{#1}\outer\def\defun@name{#2}%
\fnindexbold{#2}%
\@ifnextchar[{\@defmacpackage}{\@defmacnopackage}
}

\def\@defmacpackage[#1]{
\setbox0\hbox{\defun@hspace$\lbrack$\it\defun@type\/$\rbrack$}\relax
\setbox1\hbox{\tt#1:\defun@name\defun@hspace}\relax
\@defmac
}

\def\@defmacnopackage{
\setbox0\hbox{\defun@hspace$\lbrack$\it\defun@type\/$\rbrack$}\relax
\setbox1\hbox{\tt\defun@name\defun@hspace}\relax
\@defmac
}

\def\@defmac#1{
\above@defun
\setbox2\hbox{\hskip\textwidth\hskip-1\wd0\hskip-1\wd1}\relax
\def\args##1{##1}%
\leavevmode\hbox to 0pt{\hbox 
	to \textwidth{\hss\box0}\hss}{\box1\begin{minipage}[t]{1\wd2}
		\begin{tabbing}
#1\end{tabbing}\end{minipage}}
\below@defun
}

%% Variables
\def\defvar{\defun@vspace\defvarx}
\def\defvarx{\@defvr{Variable}}
\def\defconst{\defun@vspace\defconstx}
\def\defconstx{\@defvr{Constant}}
\def\defvr{\defun@vspace\@defvr}
\def\defvrx{\@defvr}
\def\enddefvar{\enddfn}
\def\enddefvr{\enddfn}
\def\enddefconst{\enddfn}

\def\@defvr#1#2{\outer\def\defun@type{#1}\outer\def\defun@name{#2}%
\vrindexbold{#2}%
\@ifnextchar[{\@defvarpackage}{\@defvarnopackage}
}

\def\@defvarpackage[#1]{
\setbox0\hbox{\defun@hspace$\lbrack$\it\defun@type\/$\rbrack$}\relax
\setbox1\hbox{\tt#1:\defun@name\defun@hspace}\relax
\@defvar
}

\def\@defvarnopackage{
\setbox0\hbox{\defun@hspace$\lbrack$\it\defun@type\/$\rbrack$}\relax
\setbox1\hbox{\tt\defun@name\defun@hspace}\relax
\@defvar
}

\def\@defvar{
\above@defun
\setbox2\hbox{\hskip\textwidth\hskip-1\wd0\hskip-1\wd1}\relax
\leavevmode\hbox to 0pt{\hbox 
	to \textwidth{\hss\box0}\hss}{\box1}
\below@defun
}

% The following is taken from /usr/local/lib/tex/macros/latex.tex
% but corrects a scoping bug.

\newdimen\@curtabmardimen
\def\@startline{\global\@curtabmar\@nxttabmar\relax
   \global\@curtabmardimen\dimen\@curtabmar
   \global\@curtab\@curtabmar\global\setbox\@curline\hbox
    {}\@startfield\strut}

\def\@stopline{\unskip\@stopfield\if@rjfield \global\@rjfieldfalse
   \@tempdima\@totalleftmargin \advance\@tempdima\linewidth
   \hbox to\@tempdima{\@itemfudge\hskip\@curtabmardimen
   \box\@curline\hfil\box\@curfield}\else\@addfield
   \hbox{\@itemfudge\hskip\@curtabmardimen\box\@curline}\fi}

% End of material from /usr/local/lib/tex/macros/latex.tex .

% Assume Lisp is case insensitive and force to lower case.
%\def\vindex#1{\vrindex{\lowercase{#1}}}
%\def\findex#1{\fnindex{\lowercase{#1}}}

% and restore @'s old catcode.
%
\catcode`@ = \@oldatcatcode

% and restore &'s old catcode.
%
\catcode`& = \@oldandcatcode