src/Tools/8bit/doc/manual.itex

Initial revision

\documentclass[]{article}
\usepackage{latexsym,amssymb,isa2latex}

\newcommand{\bt}[1]{{\tt #1}}

\title{The Isabelle 8bit Package}
\author{
David von Oheimb and Franz Regensburger\\
Technical University of Munich, Germany\\
E-mail: \bt{\{oheimb|regensbu\}@informatik.tu-muenchen.de}
}
\date{\today}

\begin{document}
\maketitle




\section{Introduction}

The 8bit package enables you to view, edit and print Isabelle files and perform
proofs in a quite pleasant form. 

Instead of representing logical operators with ASCII character sequences, 
a special graphical character font, resp. a \LaTeX{} 
command format, is provided. There are editors and a terminal
capable of inputting and displaying the graphical characters, and converters
between the different representations. The graphical font extends the normal
ASCII 7bit character coding with (non-standard) character codes having the
8th bit set. All this is described in section \ref{graph} of this manual.

Even without employing the 8bit font, the \LaTeX{} output for 
Isabelle files can be used for manuals, papers etc. This is the focus of
section \ref{latex}.




\section{Graphical Isabelle}
\label{graph}

This section describes the main purpose of the 8bit package, which is to provide
an extension to the ASCII character set that allows to formulate and display 
many logical operators as graphical symbols. 

\subsection{Usage}

To employ the graphical font within Isabelle, just (re-)formulate the 
logical operators of your Isabelle theory (and proof) files using this font. 
A graphical terminal and suitable editors are described in subsection 
\ref{commands}.

As a typical example, consider the following fragment of an Isabelle theory, 
an alternative formulation of the bounded universal quantifier within the 
set theory of \bt{HOL}.

\label{ex}
Without graphical characters, the operator is defined as follows.
\I@isa
consts	
    	Ball	:: "'a set => ('a => bool) => bool"
syntax
	"@Ball"	:: "pttrn => 'a set => bool => bool"	("(3!_:_./ _)" 10)
translations
		"!x:A. P" == "Ball A (%x. P)"
defs
     Ball_def	"Ball A P == ! x. x:A --> P x"
\I@isa

Using the graphical font (and assuming a corresponding re-formulation of 
\bt{HOL} operators), the definition of the operator can be improved to the following.

\I@isa
consts
	Ball	:: "'a set ë ('a ë bool) ë bool"
syntax
	"GBall"	:: "pttrn ë 'a set ë bool ë bool"	("(3Â_Î_./ _)" 10)
translations
		"ÂxÎA. P" == "Ball A (³x. P)"
defs
     Ball_def	"Ball A P Ú Âx. xÎA çè P x"
\I@isa

Note the appearance of the graphical characters, which makes the code much more
legible.

\label{compat}
It is also possible to retain pure ASCII versions of the logical operators while
offering the possibility of graphical input and output.
This may be necessary for compatibility reasons or for providing
graphical versions of the meta logic \I@Pure\I@ or object logics already
defined. In these cases, the graphical syntax can be supplied additionally with 
appropriate \I@types\I@, \I@syntax\I@, and \I@translations\I@ sections, as done
for example in the Isabelle distribution of \bt{HOL}.

In the example given above, the ASCII formulation of the quantifier can be
augmented with a graphical version by the following definition.

\I@isa
syntax
	"GBall"	:: "pttrn => 'a set => bool => bool"	("(3Â_Î_./ _)" 10)
translations
		"ÂxÎA. P" == "!x:A. P"
\I@isa

With this approach, the operators can still be entered in ASCII form, which is
important for the usability of old (pure ASCII) Isabelle files, while they are
displayed in the new graphical form. The additional level of syntax 
translations introduced in this way may interfere with other translation rules
and should therefore be designed carefully.


\subsection{User commands}
\label{commands}


A number of commands for manipulating files with graphical characters are 
available, as described in this subsection.

\subsubsection{Editors}

The first group of commands includes versions of the most common editors that 
can handle the graphical font for both keyboard input and display input. 
See the files \bt{doc/\{fontindex|keyindex|fkmatrix\}.dvi} for the keystrokes
defined for inputting the special characters. The editors are

\begin{itemize}
\item \bt{isa\_xemacs}		replaces \bt{xemacs}. You may provide a 
				specific init file called 
				\bt{.emacs\_isa\_xemacs} (in your home directory)
				that is executed after the \bt{.emacs} file.
\item \bt{isa\_gnu\_emacs}	replaces \bt{emacs}. You may provide a 
				specific init file called 
				\bt{.emacs\_isa\_gnu\_emacs} (in your home 
				directory) that is executed after the 
				\bt{.emacs} file.
\item \bt{isaaxe}		replaces \bt{axe}
\item \bt{isavim}		replaces \bt{vim}
\end{itemize}

For example, as \bt{emacs} user you may type
\bt{isa\_xemacs doc/Set2g.thy \&} to view and edit
the above sample theory fragment.

\subsubsection{Display commands}

The next group of commands is used to display files using the graphical font.
With the terminal, of course also input is possible, using the same keystrokes
as with the editors.

\begin{itemize}
\item \bt{isaterm} 		replaces \bt{xterm}. This is used as terminal
				for your ML interpreter running Isabelle with
				theories and proofs containing graphical 
				characters. This terminal is also useful if
				you want to \bt{cat} or \bt{grep} the Isabelle
				files within your shell, and as
				environment for commands like \bt{isapal}.
\item \bt{isapal}		shows the palette of available graphical 
				characters. A man page is available.
\item \bt{codetable}		prints all 8bit characters with their codes
\item \bt{isa\_xmosaic}	replaces \bt{xmosaic}. This is useful for
				browsing the index files of Isabelle theories
				(with graphical operators) that are generated
				if \I@make_html\I@ is set to \I@true\I@.
\end{itemize}

\subsubsection{Converters}
\label{conv}

The last group of commands is built to enable conversion between ASCII, 8bit 
font and
\LaTeX\ representations of the graphical characters within papers, manuals, 
and Isabelle theory and proof files. For the options of the converters, see 
the corresponding man pages.

\begin{itemize}
\item \bt{isa2latex}	converts a file with 8bit characters to a LaTeX
			source. Pure ASCII input and conversion of 8bit 
			characters to their ASCII representations is also 
			possible.
\item \bt{a2isa}	converts Isabelle files, from ASCII to 8bit characters.
			It is used mainly to convert old files.
\end{itemize}

In order to output the first theory fragment (formulated without the 8bit
font) in subsection \ref{ex} as LaTeX\ source using suitable graphical 
characters, type\\
\bt{isa2latex -s -A -o Set2.tex doc/Set2\_a.thy}.\\
(It was necessary to insert some blank characters in the file \bt{Set2\_a.thy} 
that enable \bt{isa2latex} to recognize all the operators intended to be 
printed with graphical characters, as discussed in subsection \ref{ambig}.)

For conversion of \bt{Set2.thy} to 8bit characters, type\\
\bt{a2isa -o Set2\_g.thy doc/Set2.thy}.

Further explanations of the use of the converter \bt{isa2latex} are given
in section \ref{latex}.




\section{\LaTeX\ output}
\label{latex}

Independently of whether Isabelle files are formulated with the graphical font
or not, they can be converted to \LaTeX\ source using \bt{isa2latex}
and in this way (pretty-)printed with the familiar symbols for quantification, 
intersection, etc. The tool \bt{isa2latex} can also convert \LaTeX\ source
files containing Isabelle source to pure \LaTeX\ 
files, by converting the special character sequences of the Isabelle parts to
appropriate \LaTeX\ commands, and handing through the rest (almost) verbatim.

For example, this manual itself is converted to a \bt{.tex} file by \\
\bt{isa2latex -x -e -o manual.tex doc/manual.itex}

\subsection{Conversion modes}

To handle the different parts of an input file, \bt{isa2latex} has several 
conversion modes, namely
\begin{itemize}
\item \bt{LATEX}: The input is is literally copied to the output,
without conversion of any characters. This mode is used for the \LaTeX\ parts
 of the input document.

\item \bt{INLINE}: The conversion of characters and scanning for 
multi character sequences is active, while newline and tab characters are 
treated as single blank character.
Use this mode for inserting small parts of Isabelle source within 
a line of text.

\item \bt{ISA}: The conversion of characters and scanning for 
multi character sequences is active, while newline and tab characters are 
treated according to an open tabbing environment. 
This mode is used for displaying multiple lines of Isabelle source.

\item \bt{ESC}: In this mode the input is literally copied to the output.
This mode is intended as an escape mode from the \bt{INLINE} and \bt{ESC} modes.
\end{itemize}

Upon entrance of the conversion modes, \bt{isa2latex} generates the \LaTeX\ 
commands \bt{\mbox{$\backslash$}isamode} for \bt{ISA}, 
\bt{\mbox{$\backslash$}isainline} for \bt{INLINE}, 
and \bt{\mbox{$\backslash$}isaescape} for the \bt{ESC} mode. These act as
environment delimiters and may also set the appropriate fonts, styles etc. The 
commands 
are defined in the file \bt{latex/isa2latex.sty} and may be adapted as desired.

\subsection{Conversion mode switching}

The initial conversion mode of \bt{isa2latex} and the set of available modes 
depend on the options given on the command line. Switching of the modes
relies on special toggles (like \I@\I\E@\E@@isa\I@, within the input
file) that indicate the beginning and end of the different parts of the input.

The following diagrams show the initial mode (enclosed in sqare brackets), 
the available mode switches (in the arrow symbols)
and the modes reachable with them.

If the \bt{-x} option is not given:

\I@isa
[ISA]  <-- \E\E@\E@@ -->  ESC
\I@isa

If the \bt{-x} option is given:

\I@isa
[LATEX]  <-- \I\E@\E@@ -->  INLINE  <-- \E\E@\E@@ -->  ESC
   ^
   |------ \I\E@\E@@isa -->  ISA  <-- \E\E@\E@@ -->  ESC
\I@isa


\subsection{Ambiguity problems}
\label{ambig}

As \bt{isa2latex} converts its input files on a lexical level, it has limited
capability of dealing with ambiguities that are caused by using the same 
characters for different operators. A typical examle
is the `\I@|\I@' character, which is used within the object logic \bt{HOL} both
as disjunction operator and as separator within \I@case\I@ expressions. In the
former case, it should be converted to `\I@Á\I@', and in the latter case 
retained as `\I@|\I@'. 

As a workaround, in the current version of \bt{isa2latex},
such ``dangerous'' characters are converted only if followed by a blank 
character. Thus to enforce a conversion, append a blank character behind it, and
to prohibit it even if a blank character follows, you may insert a double 
\I@\E\E@\E@@\I@, i.e. the string becomes `\I@|\E\E@\E@@\E\E@\E@@ \I@'. 

You may also redefine the critical entries of the conversion tables in the file
\bt{config/conv-tables.inp}. The entry for the `\I@|\I@' character
looks like
\I@isa
>  "\|\ "		"|"		"\mbox{$\vee$}" 
\I@isa
The first string, which (as described by the verbose comments in that file)
is the lex expression for the ASCII input, could be adapted to require an 
additional blank character before the `\I@|\I@', for example.

Most of these amibiguity problems can be avoided if you decide to employ the
graphical font for your Isabelle source files. In this case, we recommend 
using this font as early as possible, in order to avoid later conversions.
For the conversion of old files, the tool \bt{a2isa} is provided. It
normally requires no changes of the original files and only minor corrections
of the files it produces. Thus the preferred way is to apply \bt{a2isa} once and
for all on the source files, correct all conversion mistakes, and then use the 
new files with the graphical font. With these files, the ambiguity problems 
should have gone.

As the converter \bt{a2isa} is a bit smarter than \bt{isa2latex} in converting
ASCII input, it is also useful if you do not employ the 8bit font directly. To
convert a problematic ASCII file containing Isabelle source, first apply
\bt{a2isa} and then \bt{isa2latex} without option \bt{-A}. For example, type\\
\bt{a2isa Set2.thy | isa2latex -s -o doc/Set2a.tex}\\
to generate a better output than in the example conversion given in subsection
\ref{conv}.


\section{Technical issues}

\subsection{Preparations}

To use the 8bit package, you have to set resp. extend the content of the 
following environment variables:

\begin{itemize}
\item \bt{ISABELLE8BIT}: set the directory of the Isabelle 8bit package,\\
	e.g.  \bt{/usr/proj/isabelle/src/Tools/8bit}

\item \bt{PATH}: add the absolute path of the executables,\\
	e.g.  \bt{\$ISABELLE8BIT/bin}

\item \bt{MANPATH}: add the absolute path of the manual pages,\\
	e.g.  \bt{\$ISABELLE8BIT/man}

\item \bt{TEXINPUTS}: add the absolute path of special LaTeX style files
			used by the 8bit package (if necessary),
	e.g. \bt{\$ISABELLE8BIT/latex:}\\
                the trailing `\bt{:}' makes latex search subdirectories!\\
	The 8bit package uses
	\begin{itemize}
	\item the AMSFONT package
        \item the supertab style (clarkson)	
        \item the special style \bt{isa2latex.sty}
	\end{itemize}
	Some of them are contained in that directory.
\end{itemize}

Before the first use of any executable of subdirectory {\tt bin}, call
the scripts \bt{fonts/install} and \bt{keyboard/install}. This is done best
in your \bt{.login} file.

\subsection{Installation and Configuration}

To install the 8bit package, change directory to \bt{\$ISABELLE8BIT} and 
run \bt{gmake} (the gnu version of \bt{make}) on the \bt{Makefile} there.

If you want to adapt the configuration of the font (keyboard bindings or
conversion tables used by \bt{isa2latex}), change directory to\\
\bt{\$ISABELLE8BIT/config} ,
edit the files \bt{key-table.inp} resp. \bt{conv-tables.inp},
and run \bt{gmake} in this directory to generate new versions of 
\bt{isa2latex}, editor support, and documentation.

For adapting the conversion table of \bt{a2isa}, change directory to \\
\bt{\$ISABELLE8BIT/c-sources/a2isa}, edit the file \bt{lex.x}
accordingly, and run \bt{gmake} there.

\subsection{Management of alternative sources}

If you retain ASCII versions of logical operators for compatibility reasons,
as described in subsection \ref{compat}, you may want to export versions of your
Isabelle theories that contain no 8bit characters. To support this, a patching
mechanism is provided as follows. Encapsulate each section of your files dealing
solely with the 8bit font with suitable begin and end pragmas (some pair of 
unique comment lines) and configure three configuration files analogously to\\
\bt{\$ISABELLE8BIT/isa-patches/HOL/\{extract|clean|add\}-HOL.cfg}.
Then you can call the \bt{patcher} with the first file to extract and store to
a file, the second to remove, and the third to re-add the 8bit section of the
Isabelle files. See also the man page of \bt{patcher}.


\end{document}