(*:maxLineLen=78:*)
theory Integration
imports Base
begin
chapter \<open>System integration\<close>
section \<open>Isar toplevel \label{sec:isar-toplevel}\<close>
text \<open>
The Isar \<^emph>\<open>toplevel state\<close> represents the outermost configuration that is
transformed by a sequence of transitions (commands) within a theory body.
This is a pure value with pure functions acting on it in a timeless and
stateless manner. Historically, the sequence of transitions was wrapped up
as sequential command loop, such that commands are applied one-by-one. In
contemporary Isabelle/Isar, processing toplevel commands usually works in
parallel in multi-threaded Isabelle/ML @{cite "Wenzel:2009" and
"Wenzel:2013:ITP"}.
\<close>
subsection \<open>Toplevel state\<close>
text \<open>
The toplevel state is a disjoint sum of empty \<open>toplevel\<close>, or \<open>theory\<close>, or
\<open>proof\<close>. The initial toplevel is empty; a theory is commenced by a @{command
theory} header; within a theory we may use theory commands such as @{command
definition}, or state a @{command theorem} to be proven. A proof state
accepts a rich collection of Isar proof commands for structured proof
composition, or unstructured proof scripts. When the proof is concluded we
get back to the (local) theory, which is then updated by defining the
resulting fact. Further theory declarations or theorem statements with
proofs may follow, until we eventually conclude the theory development by
issuing @{command end} to get back to the empty toplevel.
\<close>
text %mlref \<open>
\begin{mldecls}
@{index_ML_type Toplevel.state} \\
@{index_ML_exception Toplevel.UNDEF} \\
@{index_ML Toplevel.is_toplevel: "Toplevel.state -> bool"} \\
@{index_ML Toplevel.theory_of: "Toplevel.state -> theory"} \\
@{index_ML Toplevel.proof_of: "Toplevel.state -> Proof.state"} \\
\end{mldecls}
\<^descr> Type @{ML_type Toplevel.state} represents Isar toplevel states, which are
normally manipulated through the concept of toplevel transitions only
(\secref{sec:toplevel-transition}).
\<^descr> @{ML Toplevel.UNDEF} is raised for undefined toplevel operations. Many
operations work only partially for certain cases, since @{ML_type
Toplevel.state} is a sum type.
\<^descr> @{ML Toplevel.is_toplevel}~\<open>state\<close> checks for an empty toplevel state.
\<^descr> @{ML Toplevel.theory_of}~\<open>state\<close> selects the background theory of \<open>state\<close>,
it raises @{ML Toplevel.UNDEF} for an empty toplevel state.
\<^descr> @{ML Toplevel.proof_of}~\<open>state\<close> selects the Isar proof state if available,
otherwise it raises an error.
\<close>
text %mlantiq \<open>
\begin{matharray}{rcl}
@{ML_antiquotation_def "Isar.state"} & : & \<open>ML_antiquotation\<close> \\
\end{matharray}
\<^descr> \<open>@{Isar.state}\<close> refers to Isar toplevel state at that point --- as
abstract value.
This only works for diagnostic ML commands, such as @{command ML_val} or
@{command ML_command}.
\<close>
subsection \<open>Toplevel transitions \label{sec:toplevel-transition}\<close>
text \<open>
An Isar toplevel transition consists of a partial function on the toplevel
state, with additional information for diagnostics and error reporting:
there are fields for command name, source position, and other meta-data.
The operational part is represented as the sequential union of a list of
partial functions, which are tried in turn until the first one succeeds.
This acts like an outer case-expression for various alternative state
transitions. For example, \isakeyword{qed} works differently for a local
proofs vs.\ the global ending of an outermost proof.
Transitions are composed via transition transformers. Internally, Isar
commands are put together from an empty transition extended by name and
source position. It is then left to the individual command parser to turn
the given concrete syntax into a suitable transition transformer that
adjoins actual operations on a theory or proof state.
\<close>
text %mlref \<open>
\begin{mldecls}
@{index_ML Toplevel.keep: "(Toplevel.state -> unit) ->
Toplevel.transition -> Toplevel.transition"} \\
@{index_ML Toplevel.theory: "(theory -> theory) ->
Toplevel.transition -> Toplevel.transition"} \\
@{index_ML Toplevel.theory_to_proof: "(theory -> Proof.state) ->
Toplevel.transition -> Toplevel.transition"} \\
@{index_ML Toplevel.proof: "(Proof.state -> Proof.state) ->
Toplevel.transition -> Toplevel.transition"} \\
@{index_ML Toplevel.proofs: "(Proof.state -> Proof.state Seq.result Seq.seq) ->
Toplevel.transition -> Toplevel.transition"} \\
@{index_ML Toplevel.end_proof: "(bool -> Proof.state -> Proof.context) ->
Toplevel.transition -> Toplevel.transition"} \\
\end{mldecls}
\<^descr> @{ML Toplevel.keep}~\<open>tr\<close> adjoins a diagnostic function.
\<^descr> @{ML Toplevel.theory}~\<open>tr\<close> adjoins a theory transformer.
\<^descr> @{ML Toplevel.theory_to_proof}~\<open>tr\<close> adjoins a global goal function, which
turns a theory into a proof state. The theory may be changed before entering
the proof; the generic Isar goal setup includes an \<^verbatim>\<open>after_qed\<close> argument
that specifies how to apply the proven result to the enclosing context, when
the proof is finished.
\<^descr> @{ML Toplevel.proof}~\<open>tr\<close> adjoins a deterministic proof command, with a
singleton result.
\<^descr> @{ML Toplevel.proofs}~\<open>tr\<close> adjoins a general proof command, with zero or
more result states (represented as a lazy list).
\<^descr> @{ML Toplevel.end_proof}~\<open>tr\<close> adjoins a concluding proof command, that
returns the resulting theory, after applying the resulting facts to the
target context.
\<close>
text %mlex \<open>
The file @{"file" "~~/src/HOL/ex/Commands.thy"} shows some example Isar
command definitions, with the all-important theory header declarations for
outer syntax keywords.
\<close>
section \<open>Theory loader database\<close>
text \<open>
In batch mode and within dumped logic images, the theory database maintains
a collection of theories as a directed acyclic graph. A theory may refer to
other theories as @{keyword "imports"}, or to auxiliary files via special
\<^emph>\<open>load commands\<close> (e.g.\ @{command ML_file}). For each theory, the base
directory of its own theory file is called \<^emph>\<open>master directory\<close>: this is used
as the relative location to refer to other files from that theory.
\<close>
text %mlref \<open>
\begin{mldecls}
@{index_ML use_thy: "string -> unit"} \\
@{index_ML use_thys: "string list -> unit"} \\[0.5ex]
@{index_ML Thy_Info.get_theory: "string -> theory"} \\
@{index_ML Thy_Info.remove_thy: "string -> unit"} \\
@{index_ML Thy_Info.register_thy: "theory -> unit"} \\
\end{mldecls}
\<^descr> @{ML use_thy}~\<open>A\<close> ensures that theory \<open>A\<close> is fully up-to-date wrt.\ the
external file store; outdated ancestors are reloaded on demand.
\<^descr> @{ML use_thys} is similar to @{ML use_thy}, but handles several theories
simultaneously. Thus it acts like processing the import header of a theory,
without performing the merge of the result. By loading a whole sub-graph of
theories, the intrinsic parallelism can be exploited by the system to
speedup loading.
This variant is used by default in @{tool build} @{cite "isabelle-system"}.
\<^descr> @{ML Thy_Info.get_theory}~\<open>A\<close> retrieves the theory value presently
associated with name \<open>A\<close>. Note that the result might be outdated wrt.\ the
file-system content.
\<^descr> @{ML Thy_Info.remove_thy}~\<open>A\<close> deletes theory \<open>A\<close> and all descendants from
the theory database.
\<^descr> @{ML Thy_Info.register_thy}~\<open>text thy\<close> registers an existing theory value
with the theory loader database and updates source version information
according to the file store.
\<close>
end