(*:wrap=hard:maxLineLen=78:*)
theory JEdit
imports Base
begin
chapter {* Introduction *}
section {* Concepts and terminology *}
text {* Isabelle/jEdit is a Prover IDE that integrates \emph{parallel
proof checking} \cite{Wenzel:2009,Wenzel:2013:ITP} with
\emph{asynchronous user interaction}
\cite{Wenzel:2010,Wenzel:2012:UITP-EPTCS}, based on a
document-oriented approach to \emph{continuous proof processing}
\cite{Wenzel:2011:CICM,Wenzel:2012}. Many concepts and system
components are fit together in order to make this work. The main
building blocks are as follows.
\begin{description}
\item [PIDE] is a general framework for Prover IDEs based on
Isabelle/Scala. It is built around a concept of parallel and
asynchronous document processing, which is supported natively by the
parallel proof engine that is implemented in Isabelle/ML. The prover
discontinues the traditional TTY-based command loop, and supports
direct editing of formal source text with rich formal markup for GUI
rendering.
\item [Isabelle/ML] is the implementation and extension language of
Isabelle, see also \cite{isabelle-implementation}. It is integrated
into the logical context of Isabelle/Isar and allows to manipulate
logical entities directly. Arbitrary add-on tools may be implemented
for object-logics such as Isabelle/HOL.
\item [Isabelle/Scala] is the system programming language of
Isabelle. It extends the pure logical environment of Isabelle/ML
towards the ``real world'' of graphical user interfaces, text
editors, IDE frameworks, web services etc. Special infrastructure
allows to transfer algebraic datatypes values and formatted text
easily between ML and Scala, using asynchronous protocol commands.
\item [jEdit] is a sophisticated text editor implemented in
Java.\footnote{\url{http://www.jedit.org}} It is easily extensible
by plugins written in languages that work on the JVM, e.g.\
Scala\footnote{\url{http://www.scala-lang.org/}}.
\item [Isabelle/jEdit] is the main example application of the PIDE
framework and the default user-interface for Isabelle. It targets
both beginners and experts. Technically, Isabelle/jEdit combines a
slightly modified version of the official jEdit code base with a
special plugin for Isabelle, integrated as standalone application
for the main operating system platforms: Linux, Windows, Mac OS X.
\end{description}
The subtle differences of Isabelle/ML versus Standard ML,
Isabelle/Scala versus Scala, Isabelle/jEdit versus regular jEdit
need to be taken into account when discussing any of these PIDE
building blocks on public forums, mailing lists, or even scientific
publications.
*}
section {* The Isabelle/jEdit Prover IDE *}
text {*
\includegraphics[width=\textwidth]{isabelle-jedit}
Isabelle/jEdit consists of some plugins for the well-known jEdit
text editor \url{http://www.jedit.org}, according to the following
principles.
\begin{itemize}
\item The original jEdit look-and-feel is generally preserved,
although some default properties have been changed to accommodate
Isabelle (e.g.\ the text area font).
\item Formal Isabelle/Isar text is checked asynchronously while
editing. The user is in full command of the editor, and the prover
refrains from locking portions of the buffer.
\item Prover feedback works via colors, boxes, squiggly underline,
hyperlinks, popup windows, icons, clickable output, all based on
semantic markup produced by Isabelle in the background.
\item Using the mouse together with the modifier key @{verbatim
CONTROL} (Linux, Windows) or @{verbatim COMMAND} (Mac OS X) exposes
additional formal content via tooltips and/or hyperlinks.
\item Formal output (in popups etc.) may be explored recursively,
using the same techniques as in the editor source buffer.
\item Additional panels (e.g.\ \emph{Output}, \emph{Symbols}) are
organized by the Dockable Window Manager of jEdit, which also allows
multiple floating instances of each window class.
\item The prover process and source files are managed on the editor
side. The prover operates on timeless and stateless document
content via Isabelle/Scala.
\item Plugin options of jEdit (for the \emph{Isabelle} plugin) give
access to a selection of Isabelle/Scala options and its persistence
preferences, usually with immediate effect on the prover back-end or
editor front-end.
\item The logic image of the prover session may be specified within
Isabelle/jEdit, but this requires restart. The new image is provided
automatically by the Isabelle build tool.
\end{itemize}
*}
subsection {* Documentation *}
text {* Regular jEdit documentation is accessible via its @{verbatim
Help} menu or @{verbatim F1} keyboard shortcut. This includes a full
\emph{User's Guide} and \emph{Frequently Asked Questions} for this
sophisticated text editor.
Most of this information about jEdit is relevant for Isabelle/jEdit
as well, but one needs to keep in mind that defaults sometimes
differ, and the official jEdit documentation does not know about the
Isabelle plugin with its special support for theory editing.
*}
subsection {* Plugins *}
text {* The \emph{Plugin Manager} of jEdit allows to augment editor
functionality by JVM modules (jars) that are provided by the central
plugin repository, or one of various mirror sites. The main
\emph{Isabelle} plugin is an integral part of Isabelle/jEdit needs
to remain active at all times! A few additional plugins are bundled
with Isabelle/jEdit for convenience or out of necessity, notably
\emph{Console} with its Isabelle/Scala sub-plugin and
\emph{SideKick} with some Isabelle-specific parsers for document
tree structure.
Connecting to the plugin server infrastructure of the jEdit project
allows to update bundled plugins or to add further
functionality. This needs to be done with the usual care for such an
open bazaar, with contributions of very mixed quality. Arbitrary
combinations of add-on features are apt to cause problems.
It is advisable to start with the default configuration of
Isabelle/jEdit and develop some understanding how it is supposed to
work, before loading additional plugins at a grand scale.
*}
subsection {* Options *}
text {* Both jEdit and Isabelle have distinctive management of
persistent options. Regular jEdit options are accessible via the
dialogs for \emph{Global Options} and \emph{Plugin Options}. This
results in an environment of properties that is stored within the
\emph{settings directory} of jEdit; see also the menu
\emph{Utilities / Settings Directory}.
Isabelle system options are managed by Isabelle/Scala; see also
\cite{isabelle-sys}, especially the coverage of sessions and
command-line tools like @{tool build} or @{tool options}. Isabelle
options that are declared as \textbf{public} are exposed to the
jEdit \emph{Plugin Options} dialog, in its section \emph{Isabelle /
General}. This provides a view on Isabelle options and persistent
preferences in @{verbatim "$ISABELLE_HOME_USER/etc/preferences"},
independently of the jEdit properties in its settings directory.
Some Isabelle options that are accessible in the Isabelle/jEdit
Plugin Options dialog affect general parameters that are relevant
outside Isabelle/jEdit as well, e.g.\ @{system_option threads} or
@{system_option parallel_proofs} for the Isabelle build tool
\cite{isabelle-sys}.
\medskip Options are loaded once on startup and saved on shutdown of
Isabelle/jEdit. Editing the machine-generated files @{verbatim
"$ISABELLE_HOME_USER/jedit/properties"} or @{verbatim
"$ISABELLE_HOME_USER/etc/preferences"} manually while the
application is running is likely to cause a lost-update! *}
subsection {* Keymaps *}
text {* Keyboard shortcuts used to be managed as jEdit properties in
the past, but recent versions (2013) have a separate concept of
\emph{keymap}. The ``imported'' keymap is produced initially from
the environment of properties that is available at the first start
of the editor.
This is relevant for Isabelle/jEdit due to various fine-tuning of
default properties, and additional keyboard shortcuts for Isabelle
specific functionality. Users may change their keymap later on, but
may need to copy Isabelle-specific key bindings manually.
*}
subsection {* Look-and-feel *}
text {* jEdit is a Java/Swing application with some ambition to
support ``native'' look-and-feel on all platforms, within the limits
of what Oracle as Java provider and major operating system vendors
and distributors allow (see also \secref{sec:problems}).
Isabelle/jEdit enables platform-specific look-and-feel by default as
follows.
\begin{description}
\item[Linux] The platform-independent \emph{Nimbus} is used by
default, but the classic \emph{Metal} also works. \emph{GTK+} works
under the side-condition that the overall GTK theme is selected in a
Java/Swing friendly way.
\item[Windows] Regular \emph{Windows} is used by default, but
platform-independent \emph{Nimbus} and \emph{Metal} also work.
\item[Mac OS X] Standard \emph{Apple Aqua} is used by default.
Moreover the bundled \emph{MacOSX} plugin provides various functions
that are expected from applications on that particular platform:
quit from menu or dock, preferences menu, drag-and-drop of text
files on the application, full-screen mode for main editor windows
etc.
\end{description}
Users may experiment with different look-and-feels, but need to keep
in mind that this extra variance of GUI functionality is unlikely to
work in arbitrary combinations. The \emph{GTK+} look-and-feel is
particularly critical due to its additional dimension of ``themes''.
After changing the look-and-feel in \emph{Global Options /
Appearance}, it is advisable to restart Isabelle/jEdit in order to
take full effect.
*}
chapter {* Prover IDE functionality *}
section {* Buffers and theories *}
text {* jEdit maintains a collection of open \emph{text buffers} to
store source files. Each buffer may be associated with any number
of visible \emph{text areas}. Buffers are subject to an
\emph{editor mode} that is determined from the file type. Files
with extension \texttt{.thy} are assigned to the mode
\emph{isabelle} and treated specifically.
\medskip Isabelle theory files are automatically added to the formal
document model of Isabelle/Scala, which maintains a family of
versions of all sources for the prover. The \emph{Theories} panel
provides an overview of the status of continuous checking of theory
sources. Unlike batch sessions \cite{isabelle-sys}, theory nodes
are identified by full path names; this allows to work with multiple
(disjoint) Isabelle sessions simultaneously within the same editor
session.
Certain events to open or update buffers with theory files cause
Isabelle/jEdit to resolve dependencies of \emph{theory imports}.
The system requests to load further files into jEdit editor buffers,
to be added to the theory document model for further checking. It
is also possible to resolve dependencies automatically, depending on
the option @{system_option jedit_auto_load}.
\medskip The open text area views on theory buffers define the
visible \emph{perspective} of Isabelle/jEdit. This is taken as a
hint for document processing: the prover ensures that those parts of
a theory where the user is looking are checked, while other parts
that are presently not required are ignored.
The perspective can be changed by opening or closing text areas
windows, or scrolling within some window. It is also possible to
indicate theory nodes as \emph{required} for continuous checking in
the \emph{Theories} panel. This means such nodes and all their
imports are always processed, independently of the visibility
status. This can have significant impact on performance, though.
\medskip Formal markup of checked theory content is turned into GUI
rendering, based on a standard repertoire known from IDEs for
programming languages: colors, icons, highlighting, squiggly
underline, tooltips, hyperlinks etc. For outer syntax of
Isabelle/Isar there is some traditional syntax-highlighting, based
on static keyword tables and tokenization within the editor. In
contrast, the painting of inner syntax (term language etc.) is
based on semantic information that is reported dynamically from the
logical context. Thus the prover can provide additional markup to
help the user understanding the meaning of the text, and to produce
more text with some add-on tools (e.g.\ information messages by
automated provers or disprovers running in the background).
Such formally annotated text can be explored further by using the
@{verbatim CONTROL} modifier key on Linux and Windows, or @{verbatim
COMMAND} on Mac OS X. Hovering with the mouse while the modifier is
pressed reveals \emph{tooltips} (grey box within the text with a
yellow popup) and/or \emph{hyperlinks} (dark grey rectangle within
the text). Tooltip popups use the same rendering principles as the
main text area, and further tooltips and/or hyperlinks may be
exposed recursively by the same mechanism.
%FIXME screenshot of term "x = x" with typing/sorting
*}
section {* Isabelle symbols and fonts *}
text {* Isabelle sources consist of \emph{symbols} that extend plain
ASCII and UTF-8 (for informal text) to allow infinitely many
mathematical symbols within the formal sources. This works without
depending on particular encodings or varying Unicode standards
\cite{Wenzel:2011:CICM}.
For the prover back-end, formal text consists of ASCII characters
that are grouped according to some simple rules, e.g.\ as plain
``@{verbatim a}'' or symbolic ``@{verbatim "\<alpha>"}''.
For the editor front-end, a certain subset of symbols is rendered as
Unicode glyphs, in order to show ``@{verbatim "\<alpha>"}'' as actual
``@{text "\<alpha>"}''. This symbol interpretation is specified by the
Isabelle system distribution (in @{file
"$ISABELLE_HOME/etc/symbols"}) or by the user (in @{verbatim
"$ISABELLE_HOME_USER/etc/symbols"}).
The appendix of \cite{isabelle-isar-ref} gives an overview of the
standard interpretation of finitely many symbols from the infinite
collection. Uninterpreted symbols are shown literally.
\medskip Technically, the Unicode view on Isabelle symbols is an
\emph{encoding} in Isabelle/jEdit, which is called @{verbatim
"UTF-8-Isabelle"} and enabled by default. Sometimes such defaults
are reset accidentally, or malformed UTF-8 sequences in the text
force jEdit to fall back on a different encoding like @{verbatim
"ISO-8859-15"}. In the latter case, raw @{verbatim "\<alpha>"} will be
shown in the text buffer instead of its Unicode rendering @{text
"\<alpha>"}. The jEdit menu operation \emph{File / Reload with Encoding /
UTF-8-Isabelle} helps to resolve such problems, potentially after
repairing malformed parts of the text.
\medskip Correct rendering via Unicode requires a font that contains
glyphs for the corresponding codepoints. Most system fonts lack
that, so Isabelle/jEdit prefers its own application font @{verbatim
IsabelleText} by default, which ensures that standard collection of
Isabelle symbols are actually seen on the screen (or printer).
Note that a Java/Swing application can load additional fonts only if
they are not installed as system font already! This means some old
version of @{verbatim IsabelleText} that happens to be already
present prevents Isabelle/jEdit from using its current bundled
version. This might result in missing glyphs (black rectangles),
since obsolete versions of @{verbatim IsabelleText} lack recent
improvements of Unicode glyph coverage. This problem can be avoided
by refraining to ``install'' any version of @{verbatim IsabelleText}
in the first place.
\medskip \paragraph{Input methods.} In principle, Isabelle/jEdit
could delegate the problem to produce Isabelle symbols in their
Unicode rendering to the underlying operating system and its
\emph{input methods}. Regular jEdit also provides various ways to
work with \emph{abbreviations} to produce certain non-ASCII
characters. Since none of these standard input methods work
satisfactorily for the mathematical characters required for
Isabelle, various specific Isabelle/jEdit mechanisms are provided.
Here is a summary for practically relevant input methods for
Isabelle symbols.
\begin{enumerate}
\item The \emph{Symbols} panel with some GUI buttoms to insert
certain symbols in the text buffer. There are also tooltips to
reveal to official Isabelle representation with some additional
information about \emph{symbol abbreviations} (see below).
\item Copy / paste from decoded source files: text that is rendered
as Unicode already may get re-used to produce further such text.
This also works between different applications, e.g.\ Isabelle/jEdit
and some web browser or mail client, as long as the same Unicode
view on Isabelle symbols is used uniformly.
\item Copy / paste from prover output within Isabelle/jEdit. The
same principles as for text buffers apply, but note that \emph{copy}
in Isabelle \emph{Output} works via the keyboard shortcut @{verbatim
"C+c"}, not the jEdit menu.
\item Completion provided by Isabelle plugin (see
\secref{sec:completion}). Isabelle symbols have a canonical name
and optional abbreviations. This can be used with the text
completion mechanism of Isabelle/jEdit, to replace a prefix of the
actual symbol like @{verbatim "\<lambda>"}, or its backslashed name
@{verbatim "\\"}@{verbatim "lambda"}, or its ASCII abbreviation
@{verbatim "%"}.
The following table is an extract of the information provided by the
standard @{file "$ISABELLE_HOME/etc/symbols"} file:
\medskip
\begin{tabular}{lll}
\textbf{symbol} & \textbf{abbreviation} & \textbf{backslashed name} \\\hline
@{text "\<lambda>"} & @{verbatim "%"} & @{verbatim "\\lambda"} \\
@{text "\<Rightarrow>"} & @{verbatim "=>"} & @{verbatim "\\Rightarrow"} \\
@{text "\<Longrightarrow>"} & @{verbatim "==>"} & @{verbatim "\\Longrightarrow"} \\
@{text "\<And>"} & @{verbatim "!!"} & @{verbatim "\\And"} \\
@{text "\<equiv>"} & @{verbatim "=="} & @{verbatim "\\equiv"} \\
@{text "\<forall>"} & @{verbatim "!"} & @{verbatim "\\forall"} \\
@{text "\<exists>"} & @{verbatim "?"} & @{verbatim "\\exists"} \\
@{text "\<longrightarrow>"} & @{verbatim "-->"} & @{verbatim "\\longrightarrow"} \\
@{text "\<and>"} & @{verbatim "&"} & @{verbatim "\\and"} \\
@{text "\<or>"} & @{verbatim "|"} & @{verbatim "\\or"} \\
@{text "\<not>"} & @{verbatim "~"} & @{verbatim "\\not"} \\
@{text "\<noteq>"} & @{verbatim "~="} & @{verbatim "\\noteq"} \\
@{text "\<in>"} & @{verbatim ":"} & @{verbatim "\\in"} \\
@{text "\<notin>"} & @{verbatim "~:"} & @{verbatim "\\notin"} \\
\end{tabular}
\medskip
Note that the above abbreviations refer to the input method. The
logical notation provides ASCII alternatives that often coincide,
but deviate occasionally. Writing formal sources directly with
ASCII replacement notation like @{verbatim "!"} or @{verbatim "ALL"}
or @{verbatim "-->"} is considered very old fashioned in 2013!
\end{enumerate}
Raw Unicode characters within prover source files should be
restricted to informal parts, e.g.\ to write text in non-latin
alphabets. Mathematical symbols should be defined via the official
rendering tables, to avoid problems with portability and longterm
storage of formal text.
\paragraph{Control symbols.} There are some special control symbols
to modify the style of a single symbol (without nesting). Control
symbols may be applied to a region of selected text, either using
the \emph{Symbols} panel or keyboard shortcuts; these editor
operations produce a separate control symbol for each symbol in the
text.
\medskip
\begin{tabular}{lll}
\textbf{symbol} & style & keyboard shortcut \\\hline
@{verbatim "\<^sup>"} & superscript & @{verbatim "C+e UP"} \\
@{verbatim "\<^sub>"} & subscript & @{verbatim "C+e DOWN"} \\
@{verbatim "\<^bold>"} & bold face & @{verbatim "C+e RIGHT"} \\
& reset & @{verbatim "C+e LEFT"} \\
\end{tabular}
It is also possible to complete on @{verbatim "\\"}@{verbatim sup},
@{verbatim "\\"}@{verbatim sub}, @{verbatim "\\"}@{verbatim bold} as
for regular symbols.
*}
section {* Text completion \label{sec:completion} *}
text {*
Text completion works via some light-weight GUI popup, which is triggered by
keyboard events during the normal editing process in the main jEdit text
area and a few additional text fields. The popup interprets special keys:
@{verbatim TAB}, @{verbatim ESCAPE}, @{verbatim UP}, @{verbatim DOWN},
@{verbatim PAGE_UP}, @{verbatim PAGE_DOWN}. All other key events are passed
to the jEdit text area --- this allows to ignore unwanted completions most
of the time and continue typing quickly.
Various Isabelle plugin options control the popup behavior and immediate
insertion into buffer.
Isabelle Symbols are completed in backslashed forms, e.g.\ @{verbatim
"\\"}@{verbatim "forall"} or @{verbatim "\<forall>"} that both produce the Isabelle
symbol @{text "\<forall>"} in its Unicode rendering. Alternatively, symbol
abbreviations may be used as specified in @{file
"$ISABELLE_HOME/etc/symbols"}.
\emph{Explicit completion} works via standard jEdit shortcut @{verbatim
"C+b"}, which is remapped to action @{verbatim "isabelle.complete"}, with a
fall-back on regular @{verbatim "complete-word"} for non-Isabelle buffers.
\emph{Implicit completion} works via keyboard input on text area, with popup
or immediate insertion into buffer. Plain words require at least 3
characters to be completed.
\emph{Immediate completion} means the (unique) replacement text is inserted
into the buffer without popup. This mode ignores plain words and requires
more than one characters for symbol abbreviations. Otherwise it falls back
on completion popup.
*}
chapter {* Known problems and workarounds \label{sec:problems} *}
text {*
\begin{itemize}
\item \textbf{Problem:} Lack of dependency management for auxiliary files
that contribute to a theory (e.g.\ @{command ML_file}).
\textbf{Workaround:} Re-load files manually within the prover.
\item \textbf{Problem:} Odd behavior of some diagnostic commands with
global side-effects, like writing a physical file.
\textbf{Workaround:} Avoid such commands.
\item \textbf{Problem:} No way to delete document nodes from the overall
collection of theories.
\textbf{Workaround:} Ignore unused files. Restart whole
Isabelle/jEdit session in worst-case situation.
\item \textbf{Problem:} The Mac OS X keyboard shortcut @{verbatim
"COMMAND+COMMA"} for Preferences is in conflict with the jEdit default
binding for @{verbatim "quick-search"}.
\textbf{Workaround:} Remap in jEdit manually according to national
keyboard, e.g.\ @{verbatim "COMMAND+SLASH"} on English ones.
\item \textbf{Problem:} Keyboard shortcuts @{verbatim "C+PLUS"} and
@{verbatim "C+MINUS"} for adjusting the editor font size depend on
platform details and national keyboards.
\textbf{Workaround:} Use numeric keypad or rebind keys in the
jEdit Shortcuts options dialog.
\item \textbf{Problem:} Some Linux / X11 input methods such as IBus
tend to disrupt key event handling of Java/Swing.
\textbf{Workaround:} Do not use input methods, reset the environment
variable @{verbatim XMODIFIERS} within Isabelle settings (default in
Isabelle2013-1).
\item \textbf{Problem:} Some Linux / X11 window managers that are
not ``re-parenting'' cause problems with additional windows opened
by the Java VM. This affects either historic or neo-minimalistic
window managers like @{verbatim awesome} or @{verbatim xmonad}.
\textbf{Workaround:} Use regular re-parenting window manager.
\item \textbf{Problem:} Recent forks of Linux / X11 window managers
and desktop environments (variants of Gnome) disrupt the handling of
menu popups and mouse positions of Java/AWT/Swing.
\textbf{Workaround:} Use mainstream versions of Linux desktops.
\end{itemize}
*}
end