theory Basics
imports Base
begin
chapter {* The Isabelle system environment *}
text {* This manual describes Isabelle together with related tools and
user interfaces as seen from a system oriented view. See also the
\emph{Isabelle/Isar Reference Manual}~\cite{isabelle-isar-ref} for
the actual Isabelle input language and related concepts, and
\emph{The Isabelle/Isar Implementation
Manual}~\cite{isabelle-implementation} for the main concepts of the
underlying implementation in Isabelle/ML.
\medskip The Isabelle system environment provides the following
basic infrastructure to integrate tools smoothly.
\begin{enumerate}
\item The \emph{Isabelle settings} mechanism provides process
environment variables to all Isabelle executables (including tools
and user interfaces).
\item The raw \emph{Isabelle process} (@{executable_ref
"isabelle-process"}) runs logic sessions either interactively or in
batch mode. In particular, this view abstracts over the invocation
of the actual ML system to be used. Regular users rarely need to
care about the low-level process.
\item The main \emph{Isabelle tool wrapper} (@{executable_ref
isabelle}) provides a generic startup environment Isabelle related
utilities, user interfaces etc. Such tools automatically benefit
from the settings mechanism.
\end{enumerate}
*}
section {* Isabelle settings \label{sec:settings} *}
text {*
The Isabelle system heavily depends on the \emph{settings
mechanism}\indexbold{settings}. Essentially, this is a statically
scoped collection of environment variables, such as @{setting
ISABELLE_HOME}, @{setting ML_SYSTEM}, @{setting ML_HOME}. These
variables are \emph{not} intended to be set directly from the shell,
though. Isabelle employs a somewhat more sophisticated scheme of
\emph{settings files} --- one for site-wide defaults, another for
additional user-specific modifications. With all configuration
variables in clearly defined places, this scheme is more
maintainable and user-friendly than global shell environment
variables.
In particular, we avoid the typical situation where prospective
users of a software package are told to put several things into
their shell startup scripts, before being able to actually run the
program. Isabelle requires none such administrative chores of its
end-users --- the executables can be invoked straight away.
Occasionally, users would still want to put the @{file
"$ISABELLE_HOME/bin"} directory into their shell's search path, but
this is not required.
*}
subsection {* Bootstrapping the environment \label{sec:boot} *}
text {* Isabelle executables need to be run within a proper settings
environment. This is bootstrapped as described below, on the first
invocation of one of the outer wrapper scripts (such as
@{executable_ref isabelle}). This happens only once for each
process tree, i.e.\ the environment is passed to subprocesses
according to regular Unix conventions.
\begin{enumerate}
\item The special variable @{setting_def ISABELLE_HOME} is
determined automatically from the location of the binary that has
been run.
You should not try to set @{setting ISABELLE_HOME} manually. Also
note that the Isabelle executables either have to be run from their
original location in the distribution directory, or via the
executable objects created by the @{tool install} tool. Symbolic
links are admissible, but a plain copy of the @{file
"$ISABELLE_HOME/bin"} files will not work!
\item The file @{file "$ISABELLE_HOME/etc/settings"} is run as a
@{executable_ref bash} shell script with the auto-export option for
variables enabled.
This file holds a rather long list of shell variable assigments,
thus providing the site-wide default settings. The Isabelle
distribution already contains a global settings file with sensible
defaults for most variables. When installing the system, only a few
of these may have to be adapted (probably @{setting ML_SYSTEM}
etc.).
\item The file @{verbatim "$ISABELLE_HOME_USER/etc/settings"} (if it
exists) is run in the same way as the site default settings. Note
that the variable @{setting ISABELLE_HOME_USER} has already been set
before --- usually to something like @{verbatim
"$USER_HOME/.isabelle/IsabelleXXXX"}.
Thus individual users may override the site-wide defaults. See also
file @{file "$ISABELLE_HOME/etc/user-settings.sample"} in the
distribution. Typically, a user settings file would contain only a
few lines, just the assigments that are really changed. One should
definitely \emph{not} start with a full copy the basic @{file
"$ISABELLE_HOME/etc/settings"}. This could cause very annoying
maintainance problems later, when the Isabelle installation is
updated or changed otherwise.
\end{enumerate}
Since settings files are regular GNU @{executable_def bash} scripts,
one may use complex shell commands, such as @{verbatim "if"} or
@{verbatim "case"} statements to set variables depending on the
system architecture or other environment variables. Such advanced
features should be added only with great care, though. In
particular, external environment references should be kept at a
minimum.
\medskip A few variables are somewhat special:
\begin{itemize}
\item @{setting_def ISABELLE_PROCESS} and @{setting_def ISABELLE_TOOL} are set
automatically to the absolute path names of the @{executable
"isabelle-process"} and @{executable isabelle} executables,
respectively.
\item @{setting_ref ISABELLE_OUTPUT} will have the identifiers of
the Isabelle distribution (cf.\ @{setting ISABELLE_IDENTIFIER}) and
the ML system (cf.\ @{setting ML_IDENTIFIER}) appended automatically
to its value.
\end{itemize}
\medskip Note that the settings environment may be inspected with
the @{tool getenv} tool. This might help to figure out the effect
of complex settings scripts. *}
subsection {* Common variables *}
text {*
This is a reference of common Isabelle settings variables. Note that
the list is somewhat open-ended. Third-party utilities or interfaces
may add their own selection. Variables that are special in some
sense are marked with @{text "\<^sup>*"}.
\begin{description}
\item[@{setting_def USER_HOME}@{text "\<^sup>*"}] Is the cross-platform
user home directory. On Unix systems this is usually the same as
@{setting HOME}, but on Windows it is the regular home directory of
the user, not the one of within the Cygwin root
file-system.\footnote{Cygwin itself offers another choice whether
its HOME should point to the \texttt{/home} directory tree or the
Windows user home.}
\item[@{setting_def ISABELLE_HOME}@{text "\<^sup>*"}] is the location of the
top-level Isabelle distribution directory. This is automatically
determined from the Isabelle executable that has been invoked. Do
not attempt to set @{setting ISABELLE_HOME} yourself from the shell!
\item[@{setting_def ISABELLE_HOME_USER}] is the user-specific
counterpart of @{setting ISABELLE_HOME}. The default value is
relative to @{verbatim "$USER_HOME/.isabelle"}, under rare
circumstances this may be changed in the global setting file.
Typically, the @{setting ISABELLE_HOME_USER} directory mimics
@{setting ISABELLE_HOME} to some extend. In particular, site-wide
defaults may be overridden by a private @{verbatim
"$ISABELLE_HOME_USER/etc/settings"}.
\item[@{setting_def ISABELLE_PLATFORM}@{text "\<^sup>*"}] is automatically
set to a symbolic identifier for the underlying hardware and
operating system. The Isabelle platform identification always
refers to the 32 bit variant, even this is a 64 bit machine. Note
that the ML or Java runtime may have a different idea, depending on
which binaries are actually run.
\item[@{setting_def ISABELLE_PLATFORM64}@{text "\<^sup>*"}] is similar to
@{setting ISABELLE_PLATFORM} but refers to the proper 64 bit variant
on a platform that supports this; the value is empty for 32 bit.
Note that the following bash expression (including the quotes)
prefers the 64 bit platform, if that is available:
@{verbatim [display] "\"${ISABELLE_PLATFORM64:-$ISABELLE_PLATFORM}\""}
\item[@{setting_def ISABELLE_PROCESS}@{text "\<^sup>*"}, @{setting
ISABELLE_TOOL}@{text "\<^sup>*"}] are automatically set to the full path
names of the @{executable "isabelle-process"} and @{executable
isabelle} executables, respectively. Thus other tools and scripts
need not assume that the @{file "$ISABELLE_HOME/bin"} directory is
on the current search path of the shell.
\item[@{setting_def ISABELLE_IDENTIFIER}@{text "\<^sup>*"}] refers
to the name of this Isabelle distribution, e.g.\ ``@{verbatim
Isabelle2012}''.
\item[@{setting_def ML_SYSTEM}, @{setting_def ML_HOME},
@{setting_def ML_OPTIONS}, @{setting_def ML_PLATFORM}, @{setting_def
ML_IDENTIFIER}@{text "\<^sup>*"}] specify the underlying ML system
to be used for Isabelle. There is only a fixed set of admissable
@{setting ML_SYSTEM} names (see the @{file
"$ISABELLE_HOME/etc/settings"} file of the distribution).
The actual compiler binary will be run from the directory @{setting
ML_HOME}, with @{setting ML_OPTIONS} as first arguments on the
command line. The optional @{setting ML_PLATFORM} may specify the
binary format of ML heap images, which is useful for cross-platform
installations. The value of @{setting ML_IDENTIFIER} is
automatically obtained by composing the values of @{setting
ML_SYSTEM}, @{setting ML_PLATFORM} and the Isabelle version values.
\item[@{setting_def ISABELLE_JDK_HOME}] needs to point to a full JDK
(Java Development Kit) installation with @{verbatim javac} and
@{verbatim jar} executables. This is essential for Isabelle/Scala
and other JVM-based tools to work properly. Note that conventional
@{verbatim JAVA_HOME} usually points to the JRE (Java Runtime
Environment), not JDK.
\item[@{setting_def ISABELLE_PATH}] is a list of directories
(separated by colons) where Isabelle logic images may reside. When
looking up heaps files, the value of @{setting ML_IDENTIFIER} is
appended to each component internally.
\item[@{setting_def ISABELLE_OUTPUT}@{text "\<^sup>*"}] is a
directory where output heap files should be stored by default. The
ML system and Isabelle version identifier is appended here, too.
\item[@{setting_def ISABELLE_BROWSER_INFO}] is the directory where
theory browser information (HTML text, graph data, and printable
documents) is stored (see also \secref{sec:info}). The default
value is @{verbatim "$ISABELLE_HOME_USER/browser_info"}.
\item[@{setting_def ISABELLE_LOGIC}] specifies the default logic to
load if none is given explicitely by the user. The default value is
@{verbatim HOL}.
\item[@{setting_def ISABELLE_LINE_EDITOR}] specifies the default
line editor for the @{tool_ref tty} interface.
\item[@{setting_def ISABELLE_USEDIR_OPTIONS}] is implicitly prefixed
to the command line of any @{tool_ref usedir} invocation. This
typically contains compilation options for object-logics --- @{tool
usedir} is the basic tool for managing logic sessions (cf.\ the
@{verbatim IsaMakefile}s in the distribution).
\item[@{setting_def ISABELLE_LATEX}, @{setting_def
ISABELLE_PDFLATEX}, @{setting_def ISABELLE_BIBTEX}, @{setting_def
ISABELLE_DVIPS}] refer to {\LaTeX} related tools for Isabelle
document preparation (see also \secref{sec:tool-latex}).
\item[@{setting_def ISABELLE_TOOLS}] is a colon separated list of
directories that are scanned by @{executable isabelle} for external
utility programs (see also \secref{sec:isabelle-tool}).
\item[@{setting_def ISABELLE_DOCS}] is a colon separated list of
directories with documentation files.
\item[@{setting_def ISABELLE_DOC_FORMAT}] specifies the preferred
document format, typically @{verbatim dvi} or @{verbatim pdf}.
\item[@{setting_def DVI_VIEWER}] specifies the command to be used
for displaying @{verbatim dvi} files.
\item[@{setting_def PDF_VIEWER}] specifies the command to be used
for displaying @{verbatim pdf} files.
\item[@{setting_def PRINT_COMMAND}] specifies the standard printer
spool command, which is expected to accept @{verbatim ps} files.
\item[@{setting_def ISABELLE_TMP_PREFIX}@{text "\<^sup>*"}] is the
prefix from which any running @{executable "isabelle-process"}
derives an individual directory for temporary files. The default is
somewhere in @{verbatim "/tmp"}.
\end{description}
*}
subsection {* Additional components \label{sec:components} *}
text {* Any directory may be registered as an explicit \emph{Isabelle
component}. The general layout conventions are that of the main
Isabelle distribution itself, and the following two files (both
optional) have a special meaning:
\begin{itemize}
\item @{verbatim "etc/settings"} holds additional settings that are
initialized when bootstrapping the overall Isabelle environment,
cf.\ \secref{sec:boot}. As usual, the content is interpreted as a
@{verbatim bash} script. It may refer to the component's enclosing
directory via the @{verbatim "COMPONENT"} shell variable.
For example, the following setting allows to refer to files within
the component later on, without having to hardwire absolute paths:
\begin{ttbox}
MY_COMPONENT_HOME="$COMPONENT"
\end{ttbox}
Components can also add to existing Isabelle settings such as
@{setting_def ISABELLE_TOOLS}, in order to provide
component-specific tools that can be invoked by end-users. For
example:
\begin{ttbox}
ISABELLE_TOOLS="$ISABELLE_TOOLS:$COMPONENT/lib/Tools"
\end{ttbox}
\item @{verbatim "etc/components"} holds a list of further
sub-components of the same structure. The directory specifications
given here can be either absolute (with leading @{verbatim "/"}) or
relative to the component's main directory.
\end{itemize}
The root of component initialization is @{setting ISABELLE_HOME}
itself. After initializing all of its sub-components recursively,
@{setting ISABELLE_HOME_USER} is included in the same manner (if
that directory exists). This allows to install private components
via @{verbatim "$ISABELLE_HOME_USER/etc/components"}, although it is
often more convenient to do that programmatically via the
\verb,init_component, shell function in the \verb,etc/settings,
script of \verb,$ISABELLE_HOME_USER, (or any other component
directory). For example:
\begin{ttbox}
init_component "$HOME/screwdriver-2.0"
\end{ttbox}
This is tolerant wrt.\ missing component directories, but might
produce a warning.
\medskip More complex situations may be addressed by initializing
components listed in a given catalog file, relatively to some base
directory:
\begin{ttbox}
init_components "$HOME/my_component_store" "some_catalog_file"
\end{ttbox}
The component directories listed in the catalog file are treated as
relative to the given base directory.
See also \secref{sec:tool-components} for some tool-support for
resolving components that are formally initialized but not installed
yet.
*}
section {* The raw Isabelle process *}
text {*
The @{executable_def "isabelle-process"} executable runs bare-bones
Isabelle logic sessions --- either interactively or in batch mode.
It provides an abstraction over the underlying ML system, and over
the actual heap file locations. Its usage is:
\begin{ttbox}
Usage: isabelle-process [OPTIONS] [INPUT] [OUTPUT]
Options are:
-I startup Isar interaction mode
-P startup Proof General interaction mode
-S secure mode -- disallow critical operations
-T ADDR startup process wrapper, with socket address
-W IN:OUT startup process wrapper, with input/output fifos
-X startup PGIP interaction mode
-e MLTEXT pass MLTEXT to the ML session
-f pass 'Session.finish();' to the ML session
-m MODE add print mode for output
-q non-interactive session
-r open heap file read-only
-u pass 'use"ROOT.ML";' to the ML session
-w reset write permissions on OUTPUT
INPUT (default "\$ISABELLE_LOGIC") and OUTPUT specify in/out heaps.
These are either names to be searched in the Isabelle path, or
actual file names (containing at least one /).
If INPUT is "RAW_ML_SYSTEM", just start the bare bones ML system.
\end{ttbox}
Input files without path specifications are looked up in the
@{setting ISABELLE_PATH} setting, which may consist of multiple
components separated by colons --- these are tried in the given
order with the value of @{setting ML_IDENTIFIER} appended
internally. In a similar way, base names are relative to the
directory specified by @{setting ISABELLE_OUTPUT}. In any case,
actual file locations may also be given by including at least one
slash (@{verbatim "/"}) in the name (hint: use @{verbatim "./"} to
refer to the current directory).
*}
subsubsection {* Options *}
text {*
If the input heap file does not have write permission bits set, or
the @{verbatim "-r"} option is given explicitely, then the session
started will be read-only. That is, the ML world cannot be
committed back into the image file. Otherwise, a writable session
enables commits into either the input file, or into another output
heap file (if that is given as the second argument on the command
line).
The read-write state of sessions is determined at startup only, it
cannot be changed intermediately. Also note that heap images may
require considerable amounts of disk space (approximately
50--200~MB). Users are responsible for themselves to dispose their
heap files when they are no longer needed.
\medskip The @{verbatim "-w"} option makes the output heap file
read-only after terminating. Thus subsequent invocations cause the
logic image to be read-only automatically.
\medskip Using the @{verbatim "-e"} option, arbitrary ML code may be
passed to the Isabelle session from the command line. Multiple
@{verbatim "-e"}'s are evaluated in the given order. Strange things
may happen when errorneous ML code is provided. Also make sure that
the ML commands are terminated properly by semicolon.
\medskip The @{verbatim "-u"} option is a shortcut for @{verbatim
"-e"} passing ``@{verbatim "use \"ROOT.ML\";"}'' to the ML session.
The @{verbatim "-f"} option passes ``@{verbatim
"Session.finish();"}'', which is intended mainly for administrative
purposes.
\medskip The @{verbatim "-m"} option adds identifiers of print modes
to be made active for this session. Typically, this is used by some
user interface, e.g.\ to enable output of proper mathematical
symbols.
\medskip Isabelle normally enters an interactive top-level loop
(after processing the @{verbatim "-e"} texts). The @{verbatim "-q"}
option inhibits interaction, thus providing a pure batch mode
facility.
\medskip The @{verbatim "-I"} option makes Isabelle enter Isar
interaction mode on startup, instead of the primitive ML top-level.
The @{verbatim "-P"} option configures the top-level loop for
interaction with the Proof General user interface, and the
@{verbatim "-X"} option enables XML-based PGIP communication.
\medskip The @{verbatim "-T"} or @{verbatim "-W"} option makes
Isabelle enter a special process wrapper for interaction via the
Isabelle/Scala layer, see also @{file
"~~/src/Pure/System/isabelle_process.scala"}. The protocol between
the ML and JVM process is private to the implementation.
\medskip The @{verbatim "-S"} option makes the Isabelle process more
secure by disabling some critical operations, notably runtime
compilation and evaluation of ML source code.
*}
subsubsection {* Examples *}
text {*
Run an interactive session of the default object-logic (as specified
by the @{setting ISABELLE_LOGIC} setting) like this:
\begin{ttbox}
isabelle-process
\end{ttbox}
Usually @{setting ISABELLE_LOGIC} refers to one of the standard
logic images, which are read-only by default. A writable session
--- based on @{verbatim HOL}, but output to @{verbatim Test} (in the
directory specified by the @{setting ISABELLE_OUTPUT} setting) ---
may be invoked as follows:
\begin{ttbox}
isabelle-process HOL Test
\end{ttbox}
Ending this session normally (e.g.\ by typing control-D) dumps the
whole ML system state into @{verbatim Test} (be prepared for more
than 100\,MB):
The @{verbatim Test} session may be continued later (still in
writable state) by:
\begin{ttbox}
isabelle-process Test
\end{ttbox}
A read-only @{verbatim Test} session may be started by:
\begin{ttbox}
isabelle-process -r Test
\end{ttbox}
\medskip Note that manual session management like this does
\emph{not} provide proper setup for theory presentation. This would
require @{tool usedir}.
\bigskip The next example demonstrates batch execution of Isabelle.
We retrieve the @{verbatim Main} theory value from the theory loader
within ML (observe the delicate quoting rules for the Bash shell
vs.\ ML):
\begin{ttbox}
isabelle-process -e 'Thy_Info.get_theory "Main";' -q -r HOL
\end{ttbox}
Note that the output text will be interspersed with additional junk
messages by the ML runtime environment. The @{verbatim "-W"} option
allows to communicate with the Isabelle process via an external
program in a more robust fashion.
*}
section {* The Isabelle tool wrapper \label{sec:isabelle-tool} *}
text {*
All Isabelle related tools and interfaces are called via a common
wrapper --- @{executable isabelle}:
\begin{ttbox}
Usage: isabelle TOOL [ARGS ...]
Start Isabelle tool NAME with ARGS; pass "-?" for tool specific help.
Available tools:
\dots
\end{ttbox}
In principle, Isabelle tools are ordinary executable scripts that
are run within the Isabelle settings environment, see
\secref{sec:settings}. The set of available tools is collected by
@{executable isabelle} from the directories listed in the @{setting
ISABELLE_TOOLS} setting. Do not try to call the scripts directly
from the shell. Neither should you add the tool directories to your
shell's search path!
*}
subsubsection {* Examples *}
text {* Show the list of available documentation of the Isabelle
distribution:
\begin{ttbox}
isabelle doc
\end{ttbox}
View a certain document as follows:
\begin{ttbox}
isabelle doc system
\end{ttbox}
Query the Isabelle settings environment:
\begin{ttbox}
isabelle getenv ISABELLE_HOME_USER
\end{ttbox}
*}
end