(*:maxLineLen=78:*)
theory Environment
imports Base
begin
chapter \<open>The Isabelle system environment\<close>
text \<open>
This manual describes Isabelle together with related tools as seen from a
system oriented view. See also the \<^emph>\<open>Isabelle/Isar Reference Manual\<close> @{cite
"isabelle-isar-ref"} for the actual Isabelle input language and related
concepts, and \<^emph>\<open>The Isabelle/Isar Implementation Manual\<close> @{cite
"isabelle-implementation"} for the main concepts of the underlying
implementation in Isabelle/ML.
\<close>
section \<open>Isabelle settings \label{sec:settings}\<close>
text \<open>
Isabelle executables may depend on the \<^emph>\<open>Isabelle settings\<close> within the
process environment. This is a statically scoped collection of environment
variables, such as @{setting ISABELLE_HOME}, @{setting ML_SYSTEM}, @{setting
ML_HOME}. These variables are \<^emph>\<open>not\<close> intended to be set directly from the
shell, but are provided by Isabelle \<^emph>\<open>components\<close> their \<^emph>\<open>settings files\<close> as
explained below.
\<close>
subsection \<open>Bootstrapping the environment \label{sec:boot}\<close>
text \<open>
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.
\<^enum> 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 \<^dir>\<open>$ISABELLE_HOME/bin\<close> files will not work!
\<^enum> The file \<^file>\<open>$ISABELLE_HOME/etc/settings\<close> 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 assignments, 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.).
\<^enum> The file @{path "$ISABELLE_HOME_USER/etc/settings"} (if it
exists) is run in the same way as the site default settings. Note that the
variable @{setting ISABELLE_HOME_USER} has already been set before ---
usually to something like \<^verbatim>\<open>$USER_HOME/.isabelle/Isabelle2018\<close>.
Thus individual users may override the site-wide defaults. Typically, a
user settings file contains only a few lines, with some assignments that
are actually changed. Never copy the central
\<^file>\<open>$ISABELLE_HOME/etc/settings\<close> file!
Since settings files are regular GNU @{executable_def bash} scripts, one may
use complex shell commands, such as \<^verbatim>\<open>if\<close> or \<^verbatim>\<open>case\<close> statements to set
variables depending on the system architecture or other environment
variables. Such advanced features should be added only with great care,
though. In particular, external environment references should be kept at a
minimum.
\<^medskip>
A few variables are somewhat special, e.g. @{setting_def ISABELLE_TOOL} is
set automatically to the absolute path name of the @{executable isabelle}
executables.
\<^medskip>
Note that the settings environment may be inspected with the @{tool getenv}
tool. This might help to figure out the effect of complex settings scripts.
\<close>
subsection \<open>Common variables\<close>
text \<open>
This is a reference of common Isabelle settings variables. Note that the
list is somewhat open-ended. Third-party utilities or interfaces may add
their own selection. Variables that are special in some sense are marked
with \<open>\<^sup>*\<close>.
\<^descr>[@{setting_def USER_HOME}\<open>\<^sup>*\<close>] Is the cross-platform user home directory.
On Unix systems this is usually the same as @{setting HOME}, but on Windows
it is the regular home directory of the user, not the one of within the
Cygwin root file-system.\<^footnote>\<open>Cygwin itself offers another choice whether its
HOME should point to the @{path "/home"} directory tree or the Windows user
home.\<close>
\<^descr>[@{setting_def ISABELLE_HOME}\<open>\<^sup>*\<close>] is the location of the top-level
Isabelle distribution directory. This is automatically determined from the
Isabelle executable that has been invoked. Do not attempt to set @{setting
ISABELLE_HOME} yourself from the shell!
\<^descr>[@{setting_def ISABELLE_HOME_USER}] is the user-specific counterpart of
@{setting ISABELLE_HOME}. The default value is relative to @{path
"$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>\<open>$ISABELLE_HOME_USER/etc/settings\<close>.
\<^descr>[@{setting_def ISABELLE_PLATFORM_FAMILY}\<open>\<^sup>*\<close>] is automatically set to the
general platform family: \<^verbatim>\<open>linux\<close>, \<^verbatim>\<open>macos\<close>, \<^verbatim>\<open>windows\<close>. Note that
platform-dependent tools usually need to refer to the more specific
identification according to @{setting ISABELLE_PLATFORM64}, @{setting
ISABELLE_PLATFORM32}, @{setting ISABELLE_WINDOWS_PLATFORM64}, @{setting
ISABELLE_WINDOWS_PLATFORM32}.
\<^descr>[@{setting_def ISABELLE_PLATFORM64}\<open>\<^sup>*\<close>, @{setting_def
ISABELLE_PLATFORM32}\<open>\<^sup>*\<close>] indicate the standard Posix platform: \<^verbatim>\<open>x86_64\<close>
for 64 bit and \<^verbatim>\<open>x86\<close> for 32 bit, together with a symbolic name for the
operating system (\<^verbatim>\<open>linux\<close>, \<^verbatim>\<open>darwin\<close>, \<^verbatim>\<open>cygwin\<close>). All platforms support 64
bit executables, some platforms also support 32 bit executables.
In GNU bash scripts, it is possible to use the following expressions (with
quotes) to specify a preference of 64 bit over 32 bit:
@{verbatim [display] \<open>"${ISABELLE_PLATFORM64:-$ISABELLE_PLATFORM32}"\<close>}
In contrast, the subsequent expression prefers the old 32 bit variant (which
is only relevant for unusual applications):
@{verbatim [display] \<open>"${ISABELLE_PLATFORM32:-$ISABELLE_PLATFORM64}"\<close>}
\<^descr>[@{setting_def ISABELLE_WINDOWS_PLATFORM64}\<open>\<^sup>*\<close>, @{setting_def
ISABELLE_WINDOWS_PLATFORM32}\<open>\<^sup>*\<close>] indicate the native Windows platform.
These settings are analogous (but independent) of those for the standard
Posix subsystem: @{setting ISABELLE_PLATFORM64}, @{setting
ISABELLE_PLATFORM32}.
In GNU bash scripts, a preference for native Windows platform variants may
be specified like this (first 64 bit, second 32 bit):
@{verbatim [display] \<open>"${ISABELLE_WINDOWS_PLATFORM64:-${ISABELLE_WINDOWS_PLATFORM32:-
${ISABELLE_PLATFORM64:-$ISABELLE_PLATFORM32}}}"\<close>}
\<^descr>[@{setting ISABELLE_TOOL}\<open>\<^sup>*\<close>] is automatically set to the full path name
of the @{executable isabelle} executable.
\<^descr>[@{setting_def ISABELLE_IDENTIFIER}\<open>\<^sup>*\<close>] refers to the name of this
Isabelle distribution, e.g.\ ``\<^verbatim>\<open>Isabelle2018\<close>''.
\<^descr>[@{setting_def ML_SYSTEM}, @{setting_def ML_HOME}, @{setting_def
ML_OPTIONS}, @{setting_def ML_PLATFORM}, @{setting_def ML_IDENTIFIER}\<open>\<^sup>*\<close>]
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>\<open>$ISABELLE_HOME/etc/settings\<close> file of the distribution).
The actual compiler binary will be run from the directory @{setting
ML_HOME}, with @{setting ML_OPTIONS} as first arguments on the command line.
The optional @{setting ML_PLATFORM} may specify the binary format of ML heap
images, which is useful for cross-platform installations. The value of
@{setting ML_IDENTIFIER} is automatically obtained by composing the values
of @{setting ML_SYSTEM}, @{setting ML_PLATFORM} and the Isabelle version
values.
\<^descr>[@{setting_def ISABELLE_JDK_HOME}] points to a full JDK (Java Development
Kit) installation with \<^verbatim>\<open>javac\<close> and \<^verbatim>\<open>jar\<close> executables. Note that
conventional \<^verbatim>\<open>JAVA_HOME\<close> points to the JRE (Java Runtime Environment), not
the JDK.
\<^descr>[@{setting_def ISABELLE_JAVA_PLATFORM}] identifies the hardware and
operating system platform for the Java installation of Isabelle. That is
always the (native) 64 bit variant: \<^verbatim>\<open>x86_64-linux\<close>, \<^verbatim>\<open>x86_64-darwin\<close>,
\<^verbatim>\<open>x86_64-windows\<close>.
\<^descr>[@{setting_def ISABELLE_BROWSER_INFO}] is the directory where theory
browser information is stored as HTML and PDF (see also \secref{sec:info}).
The default value is @{path "$ISABELLE_HOME_USER/browser_info"}.
\<^descr>[@{setting_def ISABELLE_LOGIC}] specifies the default logic to load if none
is given explicitely by the user. The default value is \<^verbatim>\<open>HOL\<close>.
\<^descr>[@{setting_def ISABELLE_LINE_EDITOR}] specifies the line editor for the
@{tool_ref console} interface.
\<^descr>[@{setting_def ISABELLE_LATEX}, @{setting_def ISABELLE_PDFLATEX},
@{setting_def ISABELLE_BIBTEX}] refer to {\LaTeX} related tools for Isabelle
document preparation (see also \secref{sec:tool-latex}).
\<^descr>[@{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}).
\<^descr>[@{setting_def ISABELLE_DOCS}] is a colon separated list of directories
with documentation files.
\<^descr>[@{setting_def PDF_VIEWER}] specifies the program to be used for displaying
\<^verbatim>\<open>pdf\<close> files.
\<^descr>[@{setting_def DVI_VIEWER}] specifies the program to be used for displaying
\<^verbatim>\<open>dvi\<close> files.
\<^descr>[@{setting_def ISABELLE_TMP_PREFIX}\<open>\<^sup>*\<close>] is the prefix from which any
running Isabelle ML process derives an individual directory for temporary
files.
\<^descr>[@{setting_def ISABELLE_TOOL_JAVA_OPTIONS}] is passed to the \<^verbatim>\<open>java\<close>
executable when running Isabelle tools (e.g. @{tool build}). This is
occasionally helpful to provide more heap space, via additional options like
\<^verbatim>\<open>-Xms1g -Xmx4g\<close>.
\<close>
subsection \<open>Additional components \label{sec:components}\<close>
text \<open>
Any directory may be registered as an explicit \<^emph>\<open>Isabelle component\<close>. The
general layout conventions are that of the main Isabelle distribution
itself, and the following two files (both optional) have a special meaning:
\<^item> \<^verbatim>\<open>etc/settings\<close> holds additional settings that are initialized when
bootstrapping the overall Isabelle environment, cf.\ \secref{sec:boot}. As
usual, the content is interpreted as a GNU bash script. It may refer to
the component's enclosing directory via the \<^verbatim>\<open>COMPONENT\<close> shell variable.
For example, the following setting allows to refer to files within the
component later on, without having to hardwire absolute paths:
@{verbatim [display] \<open>MY_COMPONENT_HOME="$COMPONENT"\<close>}
Components can also add to existing Isabelle settings such as
@{setting_def ISABELLE_TOOLS}, in order to provide component-specific
tools that can be invoked by end-users. For example:
@{verbatim [display] \<open>ISABELLE_TOOLS="$ISABELLE_TOOLS:$COMPONENT/lib/Tools"\<close>}
\<^item> \<^verbatim>\<open>etc/components\<close> holds a list of further sub-components of the same
structure. The directory specifications given here can be either absolute
(with leading \<^verbatim>\<open>/\<close>) or relative to the component's main directory.
The root of component initialization is @{setting ISABELLE_HOME} itself.
After initializing all of its sub-components recursively, @{setting
ISABELLE_HOME_USER} is included in the same manner (if that directory
exists). This allows to install private components via @{path
"$ISABELLE_HOME_USER/etc/components"}, although it is often more convenient
to do that programmatically via the \<^verbatim>\<open>init_component\<close> shell function in the
\<^verbatim>\<open>etc/settings\<close> script of \<^verbatim>\<open>$ISABELLE_HOME_USER\<close> (or any other component
directory). For example:
@{verbatim [display] \<open>init_component "$HOME/screwdriver-2.0"\<close>}
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:
@{verbatim [display] \<open>init_components "$HOME/my_component_store" "some_catalog_file"\<close>}
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.
\<close>
section \<open>The Isabelle tool wrapper \label{sec:isabelle-tool}\<close>
text \<open>
The main \<^emph>\<open>Isabelle tool wrapper\<close> provides a generic startup environment for
Isabelle-related utilities, user interfaces, add-on applications etc. Such
tools automatically benefit from the settings mechanism
(\secref{sec:settings}). Moreover, this is the standard way to invoke
Isabelle/Scala functionality as a separate operating-system process.
Isabelle command-line tools are run uniformly via a common wrapper ---
@{executable_ref isabelle}:
@{verbatim [display]
\<open>Usage: isabelle TOOL [ARGS ...]
Start Isabelle TOOL with ARGS; pass "-?" for tool-specific help.
Available tools:
...\<close>}
Tools may be implemented in Isabelle/Scala or as stand-alone executables
(usually as GNU bash scripts). In the invocation of ``@{executable
isabelle}~\<open>tool\<close>'', the named \<open>tool\<close> is resolved as follows (and in the
given order).
\<^enum> An external tool found on the directories listed in the @{setting
ISABELLE_TOOLS} settings variable (colon-separated list in standard POSIX
notation).
\<^enum> If a file ``\<open>tool\<close>\<^verbatim>\<open>.scala\<close>'' is found, the source needs to define
some object that extends the class \<^verbatim>\<open>Isabelle_Tool.Body\<close>. The Scala
compiler is invoked on the spot (which may take some time), and the body
function is run with the command-line arguments as \<^verbatim>\<open>List[String]\<close>.
\<^enum> If an executable file ``\<open>tool\<close>'' is found, it is invoked as
stand-alone program with the command-line arguments provided as \<^verbatim>\<open>argv\<close>
array.
\<^enum> An internal tool that is registered in \<^verbatim>\<open>Isabelle_Tool.internal_tools\<close>
within the Isabelle/Scala namespace of \<^verbatim>\<open>Pure.jar\<close>. This is the preferred
entry-point for high-end tools implemented in Isabelle/Scala --- compiled
once when the Isabelle distribution is built. These tools are provided by
Isabelle/Pure and cannot be augmented in user-space.
There are also some administrative tools that are available from a bare
repository clone of Isabelle, but not in regular distributions.
\<close>
subsubsection \<open>Examples\<close>
text \<open>
Show the list of available documentation of the Isabelle distribution:
@{verbatim [display] \<open>isabelle doc\<close>}
View a certain document as follows:
@{verbatim [display] \<open>isabelle doc system\<close>}
Query the Isabelle settings environment:
@{verbatim [display] \<open>isabelle getenv ISABELLE_HOME_USER\<close>}
\<close>
section \<open>The raw Isabelle ML process\<close>
subsection \<open>Batch mode \label{sec:tool-process}\<close>
text \<open>
The @{tool_def process} tool runs the raw ML process in batch mode:
@{verbatim [display]
\<open>Usage: isabelle process [OPTIONS]
Options are:
-T THEORY load theory
-d DIR include session directory
-e ML_EXPR evaluate ML expression on startup
-f ML_FILE evaluate ML file on startup
-l NAME logic session name (default ISABELLE_LOGIC="HOL")
-m MODE add print mode for output
-o OPTION override Isabelle system OPTION (via NAME=VAL or NAME)
Run the raw Isabelle ML process in batch mode.\<close>}
\<^medskip>
Options \<^verbatim>\<open>-e\<close> and \<^verbatim>\<open>-f\<close> allow to evaluate ML code, before the ML process is
started. The source is either given literally or taken from a file. Multiple
\<^verbatim>\<open>-e\<close> and \<^verbatim>\<open>-f\<close> options are evaluated in the given order. Errors lead to
premature exit of the ML process with return code 1.
\<^medskip>
Option \<^verbatim>\<open>-T\<close> loads a specified theory file. This is a wrapper for \<^verbatim>\<open>-e\<close> with
a suitable @{ML use_thy} invocation.
\<^medskip>
Option \<^verbatim>\<open>-l\<close> specifies the logic session name. Option \<^verbatim>\<open>-d\<close> specifies
additional directories for session roots, see also \secref{sec:tool-build}.
\<^medskip>
The \<^verbatim>\<open>-m\<close> option adds identifiers of print modes to be made active for this
session. For example, \<^verbatim>\<open>-m ASCII\<close> prefers ASCII replacement syntax over
mathematical Isabelle symbols.
\<^medskip>
Option \<^verbatim>\<open>-o\<close> allows to override Isabelle system options for this process,
see also \secref{sec:system-options}.
\<close>
subsubsection \<open>Examples\<close>
text \<open>
The subsequent example retrieves the \<^verbatim>\<open>Main\<close> theory value from the theory
loader within ML:
@{verbatim [display] \<open>isabelle process -e 'Thy_Info.get_theory "Main"'\<close>}
Observe the delicate quoting rules for the GNU bash shell vs.\ ML. The
Isabelle/ML and Scala libraries provide functions for that, but here we need
to do it manually.
\<^medskip>
This is how to invoke a function body with proper return code and printing
of errors, and without printing of a redundant \<^verbatim>\<open>val it = (): unit\<close> result:
@{verbatim [display] \<open>isabelle process -e 'Command_Line.tool0 (fn () => writeln "OK")'\<close>}
@{verbatim [display] \<open>isabelle process -e 'Command_Line.tool0 (fn () => error "Bad")'\<close>}
\<close>
subsection \<open>Interactive mode\<close>
text \<open>
The @{tool_def console} tool runs the raw ML process with interactive
console and line editor:
@{verbatim [display]
\<open>Usage: isabelle console [OPTIONS]
Options are:
-d DIR include session directory
-l NAME logic session name (default ISABELLE_LOGIC)
-m MODE add print mode for output
-n no build of session image on startup
-o OPTION override Isabelle system OPTION (via NAME=VAL or NAME)
-r bootstrap from raw Poly/ML
-s system build mode for session image
Build a logic session image and run the raw Isabelle ML process
in interactive mode, with line editor ISABELLE_LINE_EDITOR.\<close>}
\<^medskip>
Option \<^verbatim>\<open>-l\<close> specifies the logic session name. By default, its heap image is
checked and built on demand, but the option \<^verbatim>\<open>-n\<close> skips that.
Option \<^verbatim>\<open>-r\<close> indicates a bootstrap from the raw Poly/ML system, which is
relevant for Isabelle/Pure development.
\<^medskip>
Options \<^verbatim>\<open>-d\<close>, \<^verbatim>\<open>-m\<close>, \<^verbatim>\<open>-o\<close> have the same meaning as for @{tool process}
(\secref{sec:tool-process}).
Option \<^verbatim>\<open>-s\<close> has the same meaning as for @{tool build}
(\secref{sec:tool-build}).
\<^medskip>
The Isabelle/ML process is run through the line editor that is specified via
the settings variable @{setting ISABELLE_LINE_EDITOR} (e.g.\
@{executable_def rlwrap} for GNU readline); the fall-back is to use plain
standard input/output.
The user is connected to the raw ML toplevel loop: this is neither
Isabelle/Isar nor Isabelle/ML within the usual formal context. The most
relevant ML commands at this stage are @{ML use} (for ML files) and
@{ML use_thy} (for theory files).
\<close>
section \<open>The raw Isabelle Java process \label{sec:isabelle-java}\<close>
text \<open>
The @{executable_ref isabelle_java} executable allows to run a Java process
within the name space of Java and Scala components that are bundled with
Isabelle, but \<^emph>\<open>without\<close> the Isabelle settings environment
(\secref{sec:settings}).
After such a JVM cold-start, the Isabelle environment can be accessed via
\<^verbatim>\<open>Isabelle_System.getenv\<close> as usual, but the underlying process environment
remains clean. This is e.g.\ relevant when invoking other processes that
should remain separate from the current Isabelle installation.
\<^medskip>
Note that under normal circumstances, Isabelle command-line tools are run
\<^emph>\<open>within\<close> the settings environment, as provided by the @{executable
isabelle} wrapper (\secref{sec:isabelle-tool} and \secref{sec:tool-java}).
\<close>
subsubsection \<open>Example\<close>
text \<open>
The subsequent example creates a raw Java process on the command-line and
invokes the main Isabelle application entry point:
@{verbatim [display] \<open>isabelle_java isabelle.Main\<close>}
\<close>
section \<open>YXML versus XML \label{sec:yxml-vs-xml}\<close>
text \<open>
Isabelle tools often use YXML, which is a simple and efficient syntax for
untyped XML trees. The YXML format is defined as follows.
\<^enum> The encoding is always UTF-8.
\<^enum> Body text is represented verbatim (no escaping, no special treatment of
white space, no named entities, no CDATA chunks, no comments).
\<^enum> Markup elements are represented via ASCII control characters \<open>\<^bold>X = 5\<close>
and \<open>\<^bold>Y = 6\<close> as follows:
\begin{tabular}{ll}
XML & YXML \\\hline
\<^verbatim>\<open><\<close>\<open>name attribute\<close>\<^verbatim>\<open>=\<close>\<open>value \<dots>\<close>\<^verbatim>\<open>>\<close> &
\<open>\<^bold>X\<^bold>Yname\<^bold>Yattribute\<close>\<^verbatim>\<open>=\<close>\<open>value\<dots>\<^bold>X\<close> \\
\<^verbatim>\<open></\<close>\<open>name\<close>\<^verbatim>\<open>>\<close> & \<open>\<^bold>X\<^bold>Y\<^bold>X\<close> \\
\end{tabular}
There is no special case for empty body text, i.e.\ \<^verbatim>\<open><foo/>\<close> is treated
like \<^verbatim>\<open><foo></foo>\<close>. Also note that \<open>\<^bold>X\<close> and \<open>\<^bold>Y\<close> may never occur in
well-formed XML documents.
Parsing YXML is pretty straight-forward: split the text into chunks
separated by \<open>\<^bold>X\<close>, then split each chunk into sub-chunks separated by \<open>\<^bold>Y\<close>.
Markup chunks start with an empty sub-chunk, and a second empty sub-chunk
indicates close of an element. Any other non-empty chunk consists of plain
text. For example, see \<^file>\<open>~~/src/Pure/PIDE/yxml.ML\<close> or
\<^file>\<open>~~/src/Pure/PIDE/yxml.scala\<close>.
YXML documents may be detected quickly by checking that the first two
characters are \<open>\<^bold>X\<^bold>Y\<close>.
\<close>
end