% Latex Macro package for 6.001
% done by Nikhil, November, 1988
% updated by Hal, spring 1988
% updated by Arthur, fall 1989

\documentstyle[11pt]{article}

\pagestyle{myheadings}

% ALIGN EVEN- AND ODD-NUMBERED PAGES.
\evensidemargin 35pt

% NO NUMBERING ON SECTIONS
\setcounter{secnumdepth}{0}

% HORIZONTAL MARGINS
% Left margin 1 inch (0 + 1)
\setlength{\oddsidemargin}{0in}
% Text width 6.5 inch (so right margin 1 inch).
\setlength{\textwidth}{6.5in}

% ----------------
% VERTICAL MARGINS
% Top margin 0.5 inch (-0.5 + 1)
\setlength{\topmargin}{-0.5in}
% Head height 0.25 inch (where page headers go)
\setlength{\headheight}{0.25in}
% Head separation 0.25 inch (between header and top line of text)
\setlength{\headsep}{0.25in}
% Text height 8.5 inch (so bottom margin 1.5 in)
\setlength{\textheight}{8.5in}

% ----------------
% PARAGRAPH INDENTATION
\setlength{\parindent}{0in}

% SPACE BETWEEN PARAGRAPHS
\setlength{\parskip}{\medskipamount}

% ----------------
% EVALUATION SYMBOL
\newcommand{\evalsto}{$\Longrightarrow$}

% ----------------
% STRUTS
% HORIZONTAL STRUT.  One argument (width).
\newcommand{\hstrut}[1]{\hspace*{#1}}
% VERTICAL STRUT. Two arguments (offset from baseline, height).
\newcommand{\vstrut}[2]{\rule[#1]{0in}{#2}}

% ----------------
% EMPTY BOXES OF VARIOUS WIDTHS, FOR INDENTATION
\newcommand{\hm}{\hspace*{1em}}
\newcommand{\hmm}{\hspace*{2em}}
\newcommand{\hmmm}{\hspace*{3em}}
\newcommand{\hmmmm}{\hspace*{4em}}

% ----------------
% VARIOUS CONVENIENT WIDTHS RELATIVE TO THE TEXT WIDTH, FOR BOXES.
\newlength{\hlessmm}
\setlength{\hlessmm}{\textwidth}
\addtolength{\hlessmm}{-2em}

\newlength{\hlessmmmm}
\setlength{\hlessmmmm}{\textwidth}
\addtolength{\hlessmmmm}{-4em}

% ----------------
% ``TIGHTLIST'' ENVIRONMENT (no para space between items, small indent)
\newenvironment{tightlist}%
{\begin{list}{$\bullet$}{%
    \setlength{\topsep}{0in}
    \setlength{\partopsep}{0in}
    \setlength{\itemsep}{0in}
    \setlength{\parsep}{0in}
    \setlength{\leftmargin}{1.5em}
    \setlength{\rightmargin}{0in}
    \setlength{\itemindent}{0in}
}
}%
{\end{list}
}

% ----------------
% CODE FONT (e.g. {\cf x := 0}).
\newcommand{\cf}{\footnotesize\tt}

% ----------------
% INSTRUCTION POINTER
\newcommand{\IP}{$\bullet$}
\newcommand{\goesto}{$\longrightarrow$}

% ----------------------------------------------------------------
% LISP CODE DISPLAYS.
% Lisp code displays are enclosed between \bid and \eid.
% Most characters are taken verbatim, in typewriter font,
% Except:
%  Commands are still available (beginning with \)
%  Math mode is still available (beginning with $)

\outer\def\beginlisp{%
  \begin{minipage}[t]{\linewidth}
  \begin{list}{$\bullet$}{%
    \setlength{\topsep}{0in}
    \setlength{\partopsep}{0in}
    \setlength{\itemsep}{0in}
    \setlength{\parsep}{0in}
    \setlength{\leftmargin}{1.5em}
    \setlength{\rightmargin}{0in}
    \setlength{\itemindent}{0in}
  }\item[]
  \obeyspaces
  \obeylines \footnotesize\tt}

\outer\def\endlisp{%
  \end{list}
  \end{minipage}
  }

{\obeyspaces\gdef {\ }}

% ----------------
% ILLUSTRATIONS
% This command should specify a NEWT directory for ps files for illustrations.
\def\psfileprefix{/usr/nikhil/parle/}
\def\illustration#1#2{
\vbox to #2{\vfill\special{psfile=\psfileprefix#1.ps hoffset=-72 voffset=-45}}} 

% \illuswidth is used to set up boxes around illustrations.
\newlength{\illuswidth}
\setlength{\illuswidth}{\textwidth}
\addtolength{\illuswidth}{-7pt}

% ----------------------------------------------------------------
% SCHEME CLOSURES AND PROCEDURES

% CLOSURES: TWO CIRCLES BESIDE EACH OTHER; LEFT ONE POINTS DOWN TO CODE (arg 1)
% RIGHT ONE POINTS RIGHT TO ENVIRONMENT (arg 2)
\newcommand{\closure}[2]{%
\begin{tabular}[t]{l}
\raisebox{-1.5ex}{%
  \setlength{\unitlength}{0.2ex}
  \begin{picture}(25,15)(0,-7)
   \put( 5,5){\circle{10}}
   \put( 5,5){\circle*{1}}
   \put( 5,5){\vector(0,-1){10}}
   \put(15,5){\circle{10}}
   \put(15,5){\circle*{1}}
   \put(15,5){\vector(1,0){12}}
  \end{picture}}
  \fbox{\footnotesize #2} \\
%
\hspace*{0.8ex} \fbox{\footnotesize #1}
\end{tabular}
}

% PROCEDURES: BOX CONTAINING PARAMETERS (arg 1) AND BODY (arg 2)
\newcommand{\proc}[2]{%
\begin{tabular}{l}
params: #1 \\
body: #2 \\
\end{tabular}
}

% PROBLEM SET HEADER -- args are semester and problem set or solution
% example: \psetheader{Spring Semester, 1989}{Problem set 1}
\newcommand{\psetheader}[2]{%
\markright{6.001, #1---#2}
\begin{center}
MASSACHUSETTS INSTITUTE OF TECHNOLOGY \\
Department of Electrical Engineering and Computer Science \\
6.001---Structure and Interpretation of Computer Programs \\
#1 \\
\medskip
{\bf #2}
\end{center}
}

% PROBLEM HEADER
\newcommand{\problem}[1]{{\bf #1}}

% KEYS
\newcommand{\key}[1]{\fbox{{\sc #1}}}
\newcommand{\ctrl}{\key{ctrl}--}
\newcommand{\shift}{\key{shift}--}
\newcommand{\run}{\key{run} \ }
\newcommand{\runkey}[1]{\run \key{#1}}
\newcommand{\extend}{\key{extend} \ }
\newcommand{\kkey}[1]{\key{k$_{#1}$}}

%% Examples of keys
%% \key{abort}
%% \ctrl\key{g}
%% \extend\key{logout}
%% \kkey{1}
%% \shift\kkey{1}

% ----------------------------------------------------------------
% HERE BEGINS THE DOCUMENT
% start with \begin{document}