604 lines
17 KiB
Text
604 lines
17 KiB
Text
|
\documentclass{monograph}
|
||
|
|
|
||
|
|
\usepackage{scheme}
|
||
|
|
|
||
|
|
\iflatex
|
||
|
|
\usepackage{fullpage}
|
||
|
|
\pagestyle{plain}
|
||
|
|
\fi
|
||
|
|
|
||
|
|
\ifhtml
|
||
|
|
\documenttitle[stex.css]{Introduction to stex}
|
||
|
|
\fi
|
||
|
|
|
||
|
|
\begin{document}
|
||
|
|
\title{Introduction to stex}
|
||
|
|
\author{R. Kent Dybvig and Oscar Waddell}
|
||
|
|
\date{April 2016}
|
||
|
|
\maketitle
|
||
|
|
\def\copyrightnotice{\copyright~1998--2016 R. Kent Dybvig and Oscar Waddell}
|
||
|
|
|
||
|
|
\ifhtml
|
||
|
|
\tableofcontents
|
||
|
|
\fi
|
||
|
|
|
||
|
|
\iflatex
|
||
|
|
% block paragraphs
|
||
|
|
\setlength\parskip{4pt plus 1pt}
|
||
|
|
\setlength\parindent{0pt}
|
||
|
|
\renewenvironment{quotation}
|
||
|
|
{\list{}{\listparindent 1.5em%
|
||
|
|
\itemindent 0pt%
|
||
|
|
\rightmargin \leftmargin
|
||
|
|
\parsep 0pt plus 1pt}%
|
||
|
|
\item\relax}
|
||
|
|
{\endlist}
|
||
|
|
\fi
|
||
|
|
|
||
|
|
\section{Overview}
|
||
|
|
|
||
|
|
The \emph{stex} package consists of two main programs and some supporting
|
||
|
|
items, such as make files, make-file templates, class files, and style
|
||
|
|
files.
|
||
|
|
The two main programs are \textbf{scheme-prep} and \textbf{html-prep}.
|
||
|
|
\textbf{scheme-prep} performs a conversion from ``stex''-formatted files
|
||
|
|
into latex-formatted files, while \textbf{html-prep} converts (some)
|
||
|
|
latex-formatted files into html-formatted files.
|
||
|
|
|
||
|
|
An stex file is really just a latex file extended with a handful of
|
||
|
|
commands for including Scheme code (or pretty much any other kind of code,
|
||
|
|
as long as you don't plan to use the Scheme-specific transcript support)
|
||
|
|
in a document, plus a couple of additional features rather arbitrarily
|
||
|
|
thrown in.
|
||
|
|
|
||
|
|
The subset of latex-formatted files \textbf{html-prep} is capable of
|
||
|
|
handling is rather small but has nevertheless been useful for our
|
||
|
|
purposes, which include producing html versions of a couple of books
|
||
|
|
(\emph{The Scheme Programming Language}, Editions 2--4 and the Chez Scheme
|
||
|
|
User's Guides for Versions 6--9), the scheme.com web site, class websites,
|
||
|
|
class assignments, and various other documents.
|
||
|
|
|
||
|
|
\section{Installation}
|
||
|
|
|
||
|
|
A prerequisite to building and using stex is to have Chez Scheme or
|
||
|
|
Petite Chez Scheme installed on your system.
|
||
|
|
You'll also need pdflatex, dvips, ghostscript, and netbpm.
|
||
|
|
We've run stex under Linux and OS X but have not tried to run it under
|
||
|
|
Windows.
|
||
|
|
|
||
|
|
The simplest way to install stex for your personal use is to clone the
|
||
|
|
stex directory into your home directory, cd into the stex directory,
|
||
|
|
and run make:
|
||
|
|
|
||
|
|
\schemedisplay
|
||
|
|
make BIN=\var{bindir}
|
||
|
|
\endschemedisplay
|
||
|
|
|
||
|
|
where \var{bindir} is the directory where make will find the scheme or
|
||
|
|
petite executables.
|
||
|
|
|
||
|
|
This will create a subdirectory, named for the installed Chez Scheme
|
||
|
|
machine type, containing binary versions of the programs.
|
||
|
|
|
||
|
|
You can also use ``make install'' to make stex available for other users.
|
||
|
|
|
||
|
|
\schemedisplay
|
||
|
|
sudo make install BIN=\var{bindir} LIB=\var{libdir}
|
||
|
|
\endschemedisplay
|
||
|
|
|
||
|
|
where \var{bindir} is as described above, and \var{libdir} is the
|
||
|
|
directory where the stex library directory should be installed.
|
||
|
|
|
||
|
|
\section{Usage notes}
|
||
|
|
|
||
|
|
The simplest way to get started with stex is to get this document to
|
||
|
|
build (in the doc directory) and create your own document by cloning
|
||
|
|
this document's source file (stex.stex) and make file (Makefile).
|
||
|
|
If you've installed stex in your home directory, you should be able to
|
||
|
|
build this document by running ``make'' without arguments in the doc
|
||
|
|
directory.
|
||
|
|
If you've installed stex elsewhere, you'll first have to modify the
|
||
|
|
include for Mf-stex to reflect its installed location.
|
||
|
|
|
||
|
|
Makefile is where you declare your stex sources and various other things,
|
||
|
|
like bibtex and graphics files.
|
||
|
|
If you don't have anything much more complicated than this document,
|
||
|
|
you might just need to change the line that declares the main stex entry
|
||
|
|
point, i.e., the line that reads \scheme{x = stex}, to reflect the name
|
||
|
|
of your document.
|
||
|
|
|
||
|
|
The make is orchestrated by Mf-stex, which knows how to run
|
||
|
|
\textbf{scheme-prep}, \textbf{html-prep}, \textbf{pdflatex} (multiple
|
||
|
|
times), and various other commands to produce both pdf and html versions
|
||
|
|
of the stex document.
|
||
|
|
|
||
|
|
You can also consult the more elaborate stex source and make files for the
|
||
|
|
Chez Scheme User's Guide in the csug directory of a Chez Scheme release.
|
||
|
|
|
||
|
|
\section{Basic stex commands}
|
||
|
|
|
||
|
|
\subsection{Inline code}
|
||
|
|
|
||
|
|
An stex document includes inline Scheme (or other) code via the
|
||
|
|
\scheme{\scheme} command, e.g.:
|
||
|
|
|
||
|
|
\begin{quotation}
|
||
|
|
\schemeverbatim
|
||
|
|
When called with two arguments, \scheme{cons} creates a pair of the two
|
||
|
|
arguments, e.g., \scheme{(cons 3 4)} produces \scheme{(3 . 4)}.
|
||
|
|
\endschemeverbatim
|
||
|
|
\end{quotation}
|
||
|
|
|
||
|
|
produces:
|
||
|
|
|
||
|
|
\begin{quotation}
|
||
|
|
When called with two arguments, \scheme{cons} creates a pair of the two
|
||
|
|
arguments, e.g., \scheme{(cons 3 4)} produces \scheme{(3 . 4)}.
|
||
|
|
\end{quotation}
|
||
|
|
|
||
|
|
\subsection{Code displays}
|
||
|
|
|
||
|
|
An stex document includes out-of-line Scheme (or other) code via
|
||
|
|
\scheme{\schemedisplay} and \scheme{\endschemedisplay}, e.g.:
|
||
|
|
|
||
|
|
\begin{quotation}
|
||
|
|
\schemeverbatim
|
||
|
|
\schemedisplay
|
||
|
|
(define fact
|
||
|
|
(lambda (x)
|
||
|
|
"a light year is a measure of distance"))
|
||
|
|
|
||
|
|
(define fib
|
||
|
|
(lambda (x)
|
||
|
|
"a light year is a measure of time"))
|
||
|
|
\endschemedisplay
|
||
|
|
\endschemeverbatim
|
||
|
|
\end{quotation}
|
||
|
|
|
||
|
|
produces:
|
||
|
|
|
||
|
|
\begin{quotation}
|
||
|
|
\schemedisplay
|
||
|
|
(define fact
|
||
|
|
(lambda (x)
|
||
|
|
"a light year is a measure of distance"))
|
||
|
|
|
||
|
|
(define fib
|
||
|
|
(lambda (x)
|
||
|
|
"a light year is a measure of time"))
|
||
|
|
\endschemedisplay
|
||
|
|
\end{quotation}
|
||
|
|
|
||
|
|
Within a Scheme display, \scheme{;=>} is converted into a double right arrow
|
||
|
|
($\Rightarrow$), \scheme{;->} into a single right arrow ($\rightarrow$), and
|
||
|
|
\scheme{;==} into a phantom of the same size.
|
||
|
|
This is useful for showing what a piece of code translates or evaluates to,
|
||
|
|
e.g.:
|
||
|
|
|
||
|
|
\begin{quotation}
|
||
|
|
\schemeverbatim
|
||
|
|
A \scheme{let} expression expands into a call to a \scheme{lambda}
|
||
|
|
expression, e.g.:
|
||
|
|
\schemedisplay
|
||
|
|
(let ([a 17]) ;-> ((lambda (a) (+ a a))
|
||
|
|
(+ a a)) ;== 17)
|
||
|
|
\endschemedisplay
|
||
|
|
|
||
|
|
A \scheme{let} expression first evaluates the right-hand-side
|
||
|
|
expression, then evaluates the body in an environment that binds
|
||
|
|
the left-hand-side variable to the resulting value, e.g.:
|
||
|
|
\schemedisplay
|
||
|
|
(let ([a 17]) ;=> 17
|
||
|
|
(+ a a))
|
||
|
|
\endschemedisplay
|
||
|
|
\endschemeverbatim
|
||
|
|
\end{quotation}
|
||
|
|
|
||
|
|
produces
|
||
|
|
|
||
|
|
\begin{quotation}
|
||
|
|
A \scheme{let} expression expands into a call to a \scheme{lambda}
|
||
|
|
expression, e.g.:
|
||
|
|
\schemedisplay
|
||
|
|
(let ([a 17]) ;-> ((lambda (a) (+ a a))
|
||
|
|
(+ a a)) ;== 17)
|
||
|
|
\endschemedisplay
|
||
|
|
|
||
|
|
A \scheme{let} expression first evaluates the right-hand-side
|
||
|
|
expression, then evaluates the body in an environment that binds
|
||
|
|
the left-hand-side variable to the resulting value, e.g.:
|
||
|
|
\schemedisplay
|
||
|
|
(let ([a 17]) ;=> 17
|
||
|
|
(+ a a))
|
||
|
|
\endschemedisplay
|
||
|
|
\end{quotation}
|
||
|
|
|
||
|
|
\subsection{Variables}
|
||
|
|
|
||
|
|
Code can include emphasized variables via the \scheme{\raw{{\schbackslash}var}} command, e.g.:
|
||
|
|
|
||
|
|
\begin{quotation}
|
||
|
|
\schemeverbatim
|
||
|
|
\scheme{(let ([\var{x} \var{e}]) \var{body})} binds the variable \var{x} to
|
||
|
|
the value of \var{e} in \var{body}.
|
||
|
|
\endschemeverbatim
|
||
|
|
\end{quotation}
|
||
|
|
|
||
|
|
produces:
|
||
|
|
|
||
|
|
\begin{quotation}
|
||
|
|
\scheme{(let ([\var{x} \var{e}]) \var{body})} binds the variable \var{x} to
|
||
|
|
the value of \var{e} in \var{body}.
|
||
|
|
\end{quotation}
|
||
|
|
|
||
|
|
If the text within a \scheme{\raw{{\schbackslash}var}} form contains an underscore, the
|
||
|
|
following character or bracketed subform is converted into a subscript,
|
||
|
|
e.g., \scheme{\raw{{\schbackslash}var{\schlbrace}abc\_3{\schrbrace}}}
|
||
|
|
produces \var{abc_3}, and \scheme{\raw{{\schbackslash}var{\schlbrace}7e5\_{16}{\schrbrace}}}
|
||
|
|
produces \var{7e5_{16}}.
|
||
|
|
|
||
|
|
\scheme{\raw{{\schbackslash}var}} forms may appear within a \scheme{\scheme} form, within a Scheme display
|
||
|
|
formed by \scheme{\schemedisplay} and \scheme{\endschemedisplay} commands,
|
||
|
|
or by itself outside of either.
|
||
|
|
|
||
|
|
\subsection{Raw text in code}
|
||
|
|
|
||
|
|
Raw text can be included in code via the \scheme{\raw{{\schbackslash}raw}} command.
|
||
|
|
For example:
|
||
|
|
|
||
|
|
\begin{quotation}
|
||
|
|
\schemeverbatim
|
||
|
|
\schemedisplay
|
||
|
|
(sqrt \raw{$x$}) \is \raw{$\sqrt{x}$}.
|
||
|
|
\endschemedisplay
|
||
|
|
\endschemeverbatim
|
||
|
|
\end{quotation}
|
||
|
|
|
||
|
|
produces:
|
||
|
|
|
||
|
|
\begin{quotation}
|
||
|
|
\schemedisplay
|
||
|
|
(sqrt \raw{$x$}) ;=> \raw{$\sqrt{x}$}.
|
||
|
|
\endschemedisplay
|
||
|
|
\end{quotation}
|
||
|
|
|
||
|
|
\subsection{Generated output}
|
||
|
|
|
||
|
|
Output generated by a Scheme program can be inserted into the output via
|
||
|
|
\scheme{\generated} and \scheme{\endgenerated} commands, e.g.:
|
||
|
|
|
||
|
|
\begin{quotation}
|
||
|
|
\schemeverbatim
|
||
|
|
\generated
|
||
|
|
(let ()
|
||
|
|
(define fibs
|
||
|
|
(lambda (x y n)
|
||
|
|
(if (= n 0)
|
||
|
|
'()
|
||
|
|
(cons x (fibs y (+ x y) (- n 1))))))
|
||
|
|
(let ([n 5])
|
||
|
|
(printf "first ~r primes: ~{~s~^, ~}\n" n (fibs 0 1 n))))
|
||
|
|
\endgenerated
|
||
|
|
\endschemeverbatim
|
||
|
|
\end{quotation}
|
||
|
|
|
||
|
|
produces:
|
||
|
|
|
||
|
|
\begin{quotation}
|
||
|
|
\generated
|
||
|
|
(let ()
|
||
|
|
(define fibs
|
||
|
|
(lambda (x y n)
|
||
|
|
(if (= n 0)
|
||
|
|
'()
|
||
|
|
(cons x (fibs y (+ x y) (- n 1))))))
|
||
|
|
(let ([n 5])
|
||
|
|
(printf "first ~r primes: ~{~s~^, ~}\n" n (fibs 0 1 n))))
|
||
|
|
\endgenerated
|
||
|
|
\end{quotation}
|
||
|
|
|
||
|
|
\subsection{Verbatim Scheme displays}
|
||
|
|
|
||
|
|
When special features, like \scheme{\raw{{\schbackslash}var}} forms, need to be
|
||
|
|
suppressed within a Scheme display, a document can use
|
||
|
|
\scheme{\schemeverbatim} and \scheme{\endschemeverbatim} instead of
|
||
|
|
\scheme{\schemedisplay} and \scheme{\endschemedisplay}.
|
||
|
|
This document makes extensive use of this feature.
|
||
|
|
|
||
|
|
\section{Scheme transcripts}
|
||
|
|
|
||
|
|
\subsection{Automatic transcript generation}
|
||
|
|
|
||
|
|
The \textbf{scheme-prep} package supports a
|
||
|
|
\scheme{\transcript} command for automatically generating Scheme transcripts
|
||
|
|
from input supplied in the document source.
|
||
|
|
All text from the \scheme{\transcript} marker up to and including the
|
||
|
|
\scheme{\endtranscript} marker is replaced with a transcript generated
|
||
|
|
by supplying the intervening text as the input to a Scheme caf\'e (REPL).
|
||
|
|
If the Scheme transcript needs to contain the sequence
|
||
|
|
\scheme{\endtranscript}, a different terminator may be specified as an
|
||
|
|
optional argument to \scheme{\transcript}.
|
||
|
|
The terminator must be a backslash followed by one or more alphabetic
|
||
|
|
characters, and is specified without the backslash in the optional argument.
|
||
|
|
|
||
|
|
Three pairs of commands may be redefined to customize the typesetting
|
||
|
|
of different elements within generated transcripts.
|
||
|
|
To modify the typesetting of error messages, redefine \scheme{\transerr}
|
||
|
|
and \scheme{\endtranserr}.
|
||
|
|
To modify the typesetting of user input read from the current input port
|
||
|
|
of the caf\'e, redefine \scheme{\transin} and \scheme{\endtransin}.
|
||
|
|
To modify the typesetting of program output written to the current
|
||
|
|
output port of new caf\'e, redefine \scheme{\transout} and
|
||
|
|
\scheme{\endtransout}.
|
||
|
|
|
||
|
|
For example, the following:
|
||
|
|
|
||
|
|
\begin{quotation}
|
||
|
|
\schemeverbatim
|
||
|
|
\transcript
|
||
|
|
(define f
|
||
|
|
(lambda (x) ; indentation and comments are
|
||
|
|
(if (zero? x) ; preserved in the transcript
|
||
|
|
1
|
||
|
|
(* x (f (- x 1))))))
|
||
|
|
(values f (f 0) (f 5) (f 20))
|
||
|
|
(trace f)
|
||
|
|
(f 4)
|
||
|
|
\endtranscript
|
||
|
|
\endschemeverbatim
|
||
|
|
\end{quotation}
|
||
|
|
|
||
|
|
produces:
|
||
|
|
|
||
|
|
\begin{quotation}
|
||
|
|
\transcript
|
||
|
|
(define f
|
||
|
|
(lambda (x) ; indentation and comments are
|
||
|
|
(if (zero? x) ; preserved in the transcript
|
||
|
|
1
|
||
|
|
(* x (f (- x 1))))))
|
||
|
|
(values f (f 0) (f 5) (f 20))
|
||
|
|
(trace f)
|
||
|
|
(f 4)
|
||
|
|
\endtranscript
|
||
|
|
\end{quotation}
|
||
|
|
|
||
|
|
The following example shows how to specify a different transcript
|
||
|
|
terminator and shows the default formatting imposed by \scheme{\transerr},
|
||
|
|
\scheme{\transin}, and \scheme{\transout}.
|
||
|
|
|
||
|
|
\begin{quotation}
|
||
|
|
\schemeverbatim
|
||
|
|
\transcript[\stopthistranscript]
|
||
|
|
#e4.5
|
||
|
|
(begin (display "Enter a character: ") (read-char))
|
||
|
|
(begin (display "Enter a character: ") (read-char))Z
|
||
|
|
(begin (clear-input-port) (display "Enter a character: ") (read-char))
|
||
|
|
Z
|
||
|
|
(list (read-char) (read-char) (read-char))abc def
|
||
|
|
(define silly-repl
|
||
|
|
(lambda (prompt)
|
||
|
|
(display prompt)
|
||
|
|
(let ([x (read)])
|
||
|
|
(unless (eof-object? x)
|
||
|
|
(let ([result (eval x)])
|
||
|
|
(unless (eq? result (void))
|
||
|
|
(pretty-print result))
|
||
|
|
(silly-repl prompt))))))
|
||
|
|
(silly-repl "Enter a Scheme expression: ")
|
||
|
|
(list 1
|
||
|
|
2
|
||
|
|
3)
|
||
|
|
(silly-repl "Now what? ")
|
||
|
|
(define interview
|
||
|
|
(lambda ()
|
||
|
|
(let* ([fname (begin (display "First name: ") (read))]
|
||
|
|
[lname (begin (display "Last name: ") (read))])
|
||
|
|
(printf "Hello ~a ~a!~%" fname lname))))
|
||
|
|
(interview)
|
||
|
|
john
|
||
|
|
doe
|
||
|
|
#!eof
|
||
|
|
(printf "good to be back~%")
|
||
|
|
#!eof
|
||
|
|
\stopthistranscript
|
||
|
|
\endschemeverbatim
|
||
|
|
\end{quotation}
|
||
|
|
|
||
|
|
produces:
|
||
|
|
|
||
|
|
\begin{quotation}
|
||
|
|
\transcript[\stopthistranscript]
|
||
|
|
#e4.5
|
||
|
|
(begin (display "Enter a character: ") (read-char))
|
||
|
|
(begin (display "Enter a character: ") (read-char))Z
|
||
|
|
(begin (clear-input-port) (display "Enter a character: ") (read-char))
|
||
|
|
Z
|
||
|
|
(list (read-char) (read-char) (read-char))abc def
|
||
|
|
(define silly-repl
|
||
|
|
(lambda (prompt)
|
||
|
|
(display prompt)
|
||
|
|
(let ([x (read)])
|
||
|
|
(unless (eof-object? x)
|
||
|
|
(let ([result (eval x)])
|
||
|
|
(unless (eq? result (void))
|
||
|
|
(pretty-print result))
|
||
|
|
(silly-repl prompt))))))
|
||
|
|
(silly-repl "Enter a Scheme expression: ")
|
||
|
|
(list 1
|
||
|
|
2
|
||
|
|
3)
|
||
|
|
(silly-repl "Now what? ")
|
||
|
|
(define interview
|
||
|
|
(lambda ()
|
||
|
|
(let* ([fname (begin (display "First name: ") (read))]
|
||
|
|
[lname (begin (display "Last name: ") (read))])
|
||
|
|
(printf "Hello ~a ~a!~%" fname lname))))
|
||
|
|
(interview)
|
||
|
|
john
|
||
|
|
doe
|
||
|
|
#!eof
|
||
|
|
(printf "good to be back~%")
|
||
|
|
#!eof
|
||
|
|
\stopthistranscript
|
||
|
|
\end{quotation}
|
||
|
|
|
||
|
|
Transcripts do not include a trailing prompt by design.
|
||
|
|
This is done in such a way that an explicitly displayed string that
|
||
|
|
happens to look like the prompt is not suppressed.
|
||
|
|
For example:
|
||
|
|
|
||
|
|
\begin{quotation}
|
||
|
|
\schemeverbatim
|
||
|
|
\transcript
|
||
|
|
(begin (display "> \n") (exit))
|
||
|
|
\endtranscript
|
||
|
|
\endschemeverbatim
|
||
|
|
\end{quotation}
|
||
|
|
|
||
|
|
should leave the apparent prompt alone since it is generated as program
|
||
|
|
output.
|
||
|
|
|
||
|
|
\begin{quotation}
|
||
|
|
\transcript
|
||
|
|
(begin (display "> \n") (exit))
|
||
|
|
\endtranscript
|
||
|
|
\end{quotation}
|
||
|
|
|
||
|
|
Prompt suppression works even with
|
||
|
|
changes to \scheme{waiter-prompt-string}.
|
||
|
|
For example:
|
||
|
|
|
||
|
|
\begin{quotation}
|
||
|
|
\schemeverbatim
|
||
|
|
\transcript
|
||
|
|
(waiter-prompt-string "antelope? ")
|
||
|
|
"no thanks"
|
||
|
|
\endtranscript
|
||
|
|
\endschemeverbatim
|
||
|
|
\end{quotation}
|
||
|
|
|
||
|
|
produces no trailing "antelope? " prompt:
|
||
|
|
|
||
|
|
\begin{quotation}
|
||
|
|
\transcript
|
||
|
|
(waiter-prompt-string "antelope? ")
|
||
|
|
"no thanks"
|
||
|
|
\endtranscript
|
||
|
|
\end{quotation}
|
||
|
|
|
||
|
|
\subsection{Loading initialization code}
|
||
|
|
|
||
|
|
The \scheme{stex} commands \scheme{\schemeinit} and \scheme{\endschemeinit}
|
||
|
|
are used to bracket Scheme expressions that should be evaluated without
|
||
|
|
generating a transcript of the results.
|
||
|
|
This is useful, for example, when writing the description of a programming
|
||
|
|
assignment. The solutions can be loaded via \scheme{\schemeinit} and a
|
||
|
|
transcript showing how the solutions behave can be generated using the
|
||
|
|
\scheme{\transcript} command.
|
||
|
|
|
||
|
|
For example, the following text:
|
||
|
|
|
||
|
|
\begin{quotation}
|
||
|
|
\schemeverbatim
|
||
|
|
\schemeinit
|
||
|
|
(waiter-prompt-string ">") ; restore the original prompt setting so we
|
||
|
|
; don't get "antelope?" as the prompt
|
||
|
|
(define compute-length
|
||
|
|
(lambda (x)
|
||
|
|
(cond
|
||
|
|
[(list? x) (length x)]
|
||
|
|
[(vector? x) (vector-length x)]
|
||
|
|
[(string? x) (string-length x)]
|
||
|
|
[else (errorf 'compute-length "cannot handle ~s" ls)])))
|
||
|
|
\endschemeinit
|
||
|
|
\emph{The \scheme{compute-length} procedure behaves as follows:}
|
||
|
|
\transcript
|
||
|
|
(compute-length '())
|
||
|
|
(compute-length '(a b c))
|
||
|
|
(compute-length "abcd")
|
||
|
|
(compute-length (vector 1 2 3 4 5 6))
|
||
|
|
(compute-length compute-length)
|
||
|
|
\endtranscript
|
||
|
|
\endschemeverbatim
|
||
|
|
\end{quotation}
|
||
|
|
|
||
|
|
produces the output shown below.
|
||
|
|
|
||
|
|
\begin{quotation}
|
||
|
|
\schemeinit
|
||
|
|
(waiter-prompt-string ">") ; restore the original prompt setting so we
|
||
|
|
; don't get "antelope?" as the prompt
|
||
|
|
(define compute-length
|
||
|
|
(lambda (x)
|
||
|
|
(cond
|
||
|
|
[(list? x) (length x)]
|
||
|
|
[(vector? x) (vector-length x)]
|
||
|
|
[(string? x) (string-length x)]
|
||
|
|
[else (errorf 'compute-length "cannot handle ~s" x)])))
|
||
|
|
\endschemeinit
|
||
|
|
\emph{The \scheme{compute-length} procedure behaves as follows:}
|
||
|
|
\transcript
|
||
|
|
(compute-length '())
|
||
|
|
(compute-length '(a b c))
|
||
|
|
(compute-length "abcd")
|
||
|
|
(compute-length (vector 1 2 3 4 5 6))
|
||
|
|
(compute-length compute-length)
|
||
|
|
\endtranscript
|
||
|
|
\end{quotation}
|
||
|
|
|
||
|
|
the last line of input intentionally causes an error, which is
|
||
|
|
displayed just as it would be displayed in a caf\'e.
|
||
|
|
|
||
|
|
\section{html-prep support for the \texttt{tabular} environment}
|
||
|
|
|
||
|
|
Support for tables comes with a few caveats:
|
||
|
|
|
||
|
|
\begin{enumerate}
|
||
|
|
\item \scheme{@\schlbrace\schrbrace} directives within \scheme{tabular}
|
||
|
|
column specifiers are flat-out ignored for the time being.
|
||
|
|
\item \scheme{|} directives within \scheme{tabular}
|
||
|
|
column specifiers are essentially ignored. Their only effect is
|
||
|
|
to globally enable borders for the entire HTML table.
|
||
|
|
\item \scheme{\hrule} and \scheme{\cline} are not yet implemented.
|
||
|
|
\item no warranty is expressed or implied.
|
||
|
|
\end{enumerate}
|
||
|
|
|
||
|
|
The following code:
|
||
|
|
|
||
|
|
\begin{quotation}
|
||
|
|
\begin{verbatim}
|
||
|
|
\begin{tabular}{rcl|r}
|
||
|
|
y &=& f(x) & without loss of generality \\
|
||
|
|
z & \multicolumn{2}{r}{whee} & this is fun? \\
|
||
|
|
\multicolumn{4}{c}{
|
||
|
|
\begin{tabular}{cc}
|
||
|
|
1 & 2 \\
|
||
|
|
3 & 4
|
||
|
|
\end{tabular}
|
||
|
|
} \\
|
||
|
|
a & b & c & d \\
|
||
|
|
12345 & z & \multicolumn{2}{l}{\scheme{(define x "foo")}}
|
||
|
|
\end{tabular}
|
||
|
|
\end{verbatim}
|
||
|
|
\end{quotation}
|
||
|
|
|
||
|
|
generates this table:
|
||
|
|
|
||
|
|
\begin{quotation}
|
||
|
|
\begin{tabular}{rcl|r}
|
||
|
|
y &=& f(x) & without loss of generality \\
|
||
|
|
z & \multicolumn{2}{r}{whee} & this is fun? \\
|
||
|
|
\multicolumn{4}{c}{
|
||
|
|
\begin{tabular}{cc}
|
||
|
|
1 & 2 \\
|
||
|
|
3 & 4
|
||
|
|
\end{tabular}
|
||
|
|
} \\
|
||
|
|
a & b & c & d \\
|
||
|
|
12345 & z & \multicolumn{2}{l}{\scheme{(define x "foo")}}
|
||
|
|
\end{tabular}
|
||
|
|
\end{quotation}
|
||
|
|
|
||
|
|
\end{document}
|