(* Title: Pure/Isar/toplevel.ML
ID: $Id$
Author: Markus Wenzel, TU Muenchen
Isabelle/Isar toplevel transactions.
*)
signature TOPLEVEL =
sig
exception UNDEF
type generic_theory
type node
val theory_node: node -> generic_theory option
val proof_node: node -> ProofHistory.T option
val cases_node: (generic_theory -> 'a) -> (Proof.state -> 'a) -> node -> 'a
val presentation_context: node option -> xstring option -> Proof.context
type state
val toplevel: state
val is_toplevel: state -> bool
val is_theory: state -> bool
val is_proof: state -> bool
val level: state -> int
val node_history_of: state -> node History.T
val node_of: state -> node
val node_case: (generic_theory -> 'a) -> (Proof.state -> 'a) -> state -> 'a
val context_of: state -> Proof.context
val generic_theory_of: state -> generic_theory
val theory_of: state -> theory
val proof_of: state -> Proof.state
val proof_position_of: state -> int
val enter_proof_body: state -> Proof.state
val print_state_context: state -> unit
val print_state: bool -> state -> unit
val quiet: bool ref
val debug: bool ref
val interact: bool ref
val timing: bool ref
val profiling: int ref
val skip_proofs: bool ref
exception TERMINATE
exception RESTART
exception CONTEXT of Proof.context * exn
exception TOPLEVEL_ERROR
val exn_message: exn -> string
val program: (unit -> 'a) -> 'a
type transition
val undo_limit: bool -> int option
val empty: transition
val name: string -> transition -> transition
val position: Position.T -> transition -> transition
val interactive: bool -> transition -> transition
val print: transition -> transition
val no_timing: transition -> transition
val init_theory: (bool -> theory) -> (theory -> unit) -> (theory -> unit) ->
transition -> transition
val init_empty: (state -> bool) -> (unit -> unit) -> transition -> transition
val exit: transition -> transition
val undo_exit: transition -> transition
val kill: transition -> transition
val history: (node History.T -> node History.T) -> transition -> transition
val keep: (state -> unit) -> transition -> transition
val keep': (bool -> state -> unit) -> transition -> transition
val imperative: (unit -> unit) -> transition -> transition
val theory: (theory -> theory) -> transition -> transition
val generic_theory: (generic_theory -> generic_theory) -> transition -> transition
val theory': (bool -> theory -> theory) -> transition -> transition
val begin_local_theory: bool -> (theory -> local_theory) -> transition -> transition
val end_local_theory: transition -> transition
val local_theory: xstring option -> (local_theory -> local_theory) -> transition -> transition
val present_local_theory: xstring option -> (bool -> node -> unit) -> transition -> transition
val local_theory_to_proof': xstring option -> (bool -> local_theory -> Proof.state) ->
transition -> transition
val local_theory_to_proof: xstring option -> (local_theory -> Proof.state) ->
transition -> transition
val theory_to_proof: (theory -> Proof.state) -> transition -> transition
val end_proof: (bool -> Proof.state -> Proof.context) -> transition -> transition
val forget_proof: transition -> transition
val present_proof: (bool -> node -> unit) -> transition -> transition
val proofs': (bool -> Proof.state -> Proof.state Seq.seq) -> transition -> transition
val proof': (bool -> Proof.state -> Proof.state) -> transition -> transition
val proofs: (Proof.state -> Proof.state Seq.seq) -> transition -> transition
val proof: (Proof.state -> Proof.state) -> transition -> transition
val actual_proof: (ProofHistory.T -> ProofHistory.T) -> transition -> transition
val skip_proof: (int History.T -> int History.T) -> transition -> transition
val skip_proof_to_theory: (int -> bool) -> transition -> transition
val unknown_theory: transition -> transition
val unknown_proof: transition -> transition
val unknown_context: transition -> transition
val error_msg: transition -> exn * string -> unit
val transition: bool -> transition -> state -> (state * (exn * string) option) option
val present_excursion: (transition * (state -> state -> 'a -> 'a)) list -> 'a -> 'a
val excursion: transition list -> unit
end;
structure Toplevel: TOPLEVEL =
struct
(** toplevel state **)
exception UNDEF;
(* local theory wrappers *)
type generic_theory = Context.generic; (*theory or local_theory*)
val loc_init = TheoryTarget.context;
val loc_exit = ProofContext.theory_of o LocalTheory.exit;
fun loc_begin loc (Context.Theory thy) = loc_init (the_default "-" loc) thy
| loc_begin NONE (Context.Proof lthy) = lthy
| loc_begin (SOME loc) (Context.Proof lthy) = loc_init loc (loc_exit lthy);
fun loc_finish _ (Context.Theory _) = Context.Theory o loc_exit
| loc_finish NONE (Context.Proof _) = Context.Proof o LocalTheory.restore
| loc_finish (SOME _) (Context.Proof lthy) = fn lthy' =>
Context.Proof (LocalTheory.reinit (LocalTheory.raw_theory (K (loc_exit lthy')) lthy));
(* datatype node *)
datatype node =
Theory of generic_theory * Proof.context option | (*theory with presentation context*)
Proof of ProofHistory.T * ((Proof.context -> generic_theory) * generic_theory) |
(*history of proof states, finish, original theory*)
SkipProof of int History.T * (generic_theory * generic_theory);
(*history of proof depths, resulting theory, original theory*)
val the_global_theory = fn Theory (Context.Theory thy, _) => thy | _ => raise UNDEF;
val theory_node = fn Theory (gthy, _) => SOME gthy | _ => NONE;
val proof_node = fn Proof (prf, _) => SOME prf | _ => NONE;
fun cases_node f _ (Theory (gthy, _)) = f gthy
| cases_node _ g (Proof (prf, _)) = g (ProofHistory.current prf)
| cases_node f _ (SkipProof (_, (gthy, _))) = f gthy;
fun presentation_context (SOME (Theory (_, SOME ctxt))) NONE = ctxt
| presentation_context (SOME node) NONE = cases_node Context.proof_of Proof.context_of node
| presentation_context (SOME node) (SOME loc) =
loc_init loc (cases_node Context.theory_of Proof.theory_of node)
| presentation_context NONE _ = raise UNDEF;
fun reset_presentation (Theory (gthy, _)) = Theory (gthy, NONE)
| reset_presentation node = node;
(* datatype state *)
type state_info = node History.T * ((theory -> unit) * (theory -> unit));
datatype state =
Toplevel of state_info option | (*outer toplevel, leftover end state*)
State of state_info;
val toplevel = Toplevel NONE;
fun is_toplevel (Toplevel _) = true
| is_toplevel _ = false;
fun level (Toplevel _) = 0
| level (State (node, _)) =
(case History.current node of
Theory _ => 0
| Proof (prf, _) => Proof.level (ProofHistory.current prf)
| SkipProof (h, _) => History.current h + 1); (*different notion of proof depth!*)
fun str_of_state (Toplevel _) = "at top level"
| str_of_state (State (node, _)) =
(case History.current node of
Theory (Context.Theory _, _) => "in theory mode"
| Theory (Context.Proof _, _) => "in local theory mode"
| Proof _ => "in proof mode"
| SkipProof _ => "in skipped proof mode");
(* top node *)
fun node_history_of (Toplevel _) = raise UNDEF
| node_history_of (State (node, _)) = node;
val node_of = History.current o node_history_of;
fun is_theory state = not (is_toplevel state) andalso is_some (theory_node (node_of state));
fun is_proof state = not (is_toplevel state) andalso is_some (proof_node (node_of state));
fun node_case f g state = cases_node f g (node_of state);
val context_of = node_case Context.proof_of Proof.context_of;
val generic_theory_of = node_case I (Context.Proof o Proof.context_of);
val theory_of = node_case Context.theory_of Proof.theory_of;
val proof_of = node_case (fn _ => raise UNDEF) I;
fun proof_position_of state =
(case node_of state of
Proof (prf, _) => ProofHistory.position prf
| _ => raise UNDEF);
val enter_proof_body = node_case (Proof.init o Context.proof_of) Proof.enter_forward;
(* print state *)
val pretty_context = LocalTheory.pretty o Context.cases (TheoryTarget.init NONE) I;
fun print_state_context state =
(case try node_of state of
NONE => []
| SOME (Theory (gthy, _)) => pretty_context gthy
| SOME (Proof (_, (_, gthy))) => pretty_context gthy
| SOME (SkipProof (_, (gthy, _))) => pretty_context gthy)
|> Pretty.chunks |> Pretty.writeln;
fun print_state prf_only state =
(case try node_of state of
NONE => []
| SOME (Theory (gthy, _)) => if prf_only then [] else pretty_context gthy
| SOME (Proof (prf, _)) =>
Proof.pretty_state (ProofHistory.position prf) (ProofHistory.current prf)
| SOME (SkipProof (h, _)) =>
[Pretty.str ("skipped proof: depth " ^ string_of_int (History.current h))])
|> Pretty.markup_chunks Markup.state |> Pretty.writeln;
(** toplevel transitions **)
val quiet = ref false;
val debug = Output.debugging;
val interact = ref false;
val timing = Output.timing;
val profiling = ref 0;
val skip_proofs = ref false;
exception TERMINATE;
exception RESTART;
exception EXCURSION_FAIL of exn * string;
exception FAILURE of state * exn;
exception TOPLEVEL_ERROR;
(* print exceptions *)
exception CONTEXT of Proof.context * exn;
fun exn_context NONE exn = exn
| exn_context (SOME ctxt) exn = CONTEXT (ctxt, exn);
local
fun if_context NONE _ _ = []
| if_context (SOME ctxt) f xs = map (f ctxt) xs;
fun raised name [] = "exception " ^ name ^ " raised"
| raised name [msg] = "exception " ^ name ^ " raised: " ^ msg
| raised name msgs = cat_lines (("exception " ^ name ^ " raised:") :: msgs);
in
fun exn_message e =
let
val detailed = ! debug;
fun exn_msg _ (CONTEXT (ctxt, exn)) = exn_msg (SOME ctxt) exn
| exn_msg ctxt (Exn.EXCEPTIONS (exns, "")) = cat_lines (map (exn_msg ctxt) exns)
| exn_msg ctxt (Exn.EXCEPTIONS (exns, msg)) = cat_lines (map (exn_msg ctxt) exns @ [msg])
| exn_msg ctxt (EXCURSION_FAIL (exn, loc)) =
exn_msg ctxt exn ^ Markup.markup Markup.location ("\n" ^ loc)
| exn_msg _ TERMINATE = "Exit."
| exn_msg _ RESTART = "Restart."
| exn_msg _ Interrupt = "Interrupt."
| exn_msg _ TimeLimit.TimeOut = "Timeout."
| exn_msg _ TOPLEVEL_ERROR = "Error."
| exn_msg _ (SYS_ERROR msg) = "## SYSTEM ERROR ##\n" ^ msg
| exn_msg _ (ERROR msg) = msg
| exn_msg _ (Fail msg) = raised "Fail" [msg]
| exn_msg _ (THEORY (msg, thys)) =
raised "THEORY" (msg :: (if detailed then map Context.str_of_thy thys else []))
| exn_msg _ (Syntax.AST (msg, asts)) = raised "AST" (msg ::
(if detailed then map (Pretty.string_of o Syntax.pretty_ast) asts else []))
| exn_msg ctxt (TYPE (msg, Ts, ts)) = raised "TYPE" (msg ::
(if detailed then
if_context ctxt Syntax.string_of_typ Ts @ if_context ctxt Syntax.string_of_term ts
else []))
| exn_msg ctxt (TERM (msg, ts)) = raised "TERM" (msg ::
(if detailed then if_context ctxt Syntax.string_of_term ts else []))
| exn_msg ctxt (THM (msg, i, thms)) = raised ("THM " ^ string_of_int i) (msg ::
(if detailed then if_context ctxt ProofContext.string_of_thm thms else []))
| exn_msg _ exn = raised (General.exnMessage exn) []
in exn_msg NONE e end;
end;
(* controlled execution *)
local
fun debugging f x =
if ! debug then exception_trace (fn () => f x)
else f x;
fun toplevel_error f x =
let val ctxt = try ML_Context.the_local_context () in
f x handle exn =>
(Output.error_msg (exn_message (exn_context ctxt exn)); raise TOPLEVEL_ERROR)
end;
in
fun controlled_execution f =
f
|> debugging
|> interruptible;
fun program f =
(f
|> debugging
|> toplevel_error) ();
end;
(* node transactions and recovery from stale theories *)
(*NB: proof commands should be non-destructive!*)
local
fun is_stale state = Context.is_stale (theory_of state) handle UNDEF => false;
fun is_draft_theory (Theory (gthy, _)) = Context.is_draft (Context.theory_of gthy)
| is_draft_theory _ = false;
fun stale_error NONE = SOME (ERROR "Stale theory encountered after successful execution!")
| stale_error some = some;
fun map_theory f = History.map_current
(fn Theory (gthy, ctxt) => Theory (Context.mapping f (LocalTheory.raw_theory f) gthy, ctxt)
| node => node);
in
fun transaction hist pos f (node, term) =
let
val _ = is_draft_theory (History.current node) andalso
error "Illegal draft theory in toplevel state";
val cont_node = node |> History.map_current reset_presentation;
val back_node = cont_node |> map_theory Theory.copy |> map_theory Theory.checkpoint;
fun state_error e nd = (State (nd, term), e);
val (result, err) =
cont_node
|> (f
|> (if hist then History.apply' (History.current back_node) else History.map_current)
|> controlled_execution)
|> map_theory Theory.checkpoint
|> state_error NONE
handle exn => state_error (SOME exn) cont_node;
val (result', err') =
if is_stale result then state_error (stale_error err) back_node
else (result, err);
in
(case err' of
NONE => result'
| SOME exn => raise FAILURE (result', exn))
end;
end;
(* primitive transitions *)
(*Note: Recovery from stale theories is provided only for theory-level
operations via Transaction. Other node or state operations should
not touch theories at all. Interrupts are enabled only for Keep and
Transaction.*)
datatype trans =
Init of (bool -> theory) * ((theory -> unit) * (theory -> unit)) |
(*init node; with exit/kill operation*)
InitEmpty of (state -> bool) * (unit -> unit) | (*init empty toplevel*)
Exit | (*conclude node -- deferred until init*)
UndoExit | (*continue after conclusion*)
Kill | (*abort node*)
History of node History.T -> node History.T | (*history operation (undo etc.)*)
Keep of bool -> state -> unit | (*peek at state*)
Transaction of bool * (bool -> node -> node); (*node transaction*)
fun undo_limit int = if int then NONE else SOME 0;
fun safe_exit (Toplevel (SOME (node, (exit, _)))) =
(case try the_global_theory (History.current node) of
SOME thy => controlled_execution exit thy
| NONE => ())
| safe_exit _ = ();
local
fun keep_state int f = controlled_execution (fn x => tap (f int) x);
fun apply_tr int _ (Init (f, term)) (state as Toplevel _) =
let val node = Theory (Context.Theory (Theory.checkpoint (f int)), NONE)
in safe_exit state; State (History.init (undo_limit int) node, term) end
| apply_tr int _ (InitEmpty (check, f)) (state as Toplevel _) =
if check state then (safe_exit state; keep_state int (fn _ => fn _ => f ()) toplevel)
else raise UNDEF
| apply_tr _ _ Exit (State (node, term)) =
(the_global_theory (History.current node); Toplevel (SOME (node, term)))
| apply_tr _ _ UndoExit (Toplevel (SOME state_info)) = State state_info
| apply_tr _ _ Kill (State (node, (_, kill))) =
(kill (the_global_theory (History.current node)); toplevel)
| apply_tr _ _ (History f) (State (node, term)) = State (f node, term)
| apply_tr int _ (Keep f) state = keep_state int f state
| apply_tr int pos (Transaction (hist, f)) (State state) =
transaction hist pos (fn x => f int x) state
| apply_tr _ _ _ _ = raise UNDEF;
fun apply_union _ _ [] state = raise FAILURE (state, UNDEF)
| apply_union int pos (tr :: trs) state =
apply_tr int pos tr state
handle UNDEF => apply_union int pos trs state
| FAILURE (alt_state, UNDEF) => apply_union int pos trs alt_state
| exn as FAILURE _ => raise exn
| exn => raise FAILURE (state, exn);
in
fun apply_trans int pos trs state = (apply_union int pos trs state, NONE)
handle FAILURE (alt_state, exn) => (alt_state, SOME exn) | exn => (state, SOME exn);
end;
(* datatype transition *)
datatype transition = Transition of
{name: string, (*command name*)
pos: Position.T, (*source position*)
int_only: bool, (*interactive-only*)
print: bool, (*print result state*)
no_timing: bool, (*suppress timing*)
trans: trans list}; (*primitive transitions (union)*)
fun make_transition (name, pos, int_only, print, no_timing, trans) =
Transition {name = name, pos = pos, int_only = int_only, print = print, no_timing = no_timing,
trans = trans};
fun map_transition f (Transition {name, pos, int_only, print, no_timing, trans}) =
make_transition (f (name, pos, int_only, print, no_timing, trans));
val empty = make_transition ("<unknown>", Position.none, false, false, false, []);
(* diagnostics *)
fun str_of_transition (Transition {name, pos, ...}) = quote name ^ Position.str_of pos;
fun command_msg msg tr = msg ^ "command " ^ str_of_transition tr;
fun at_command tr = command_msg "At " tr ^ ".";
fun type_error tr state =
ERROR (command_msg "Illegal application of " tr ^ " " ^ str_of_state state);
(* modify transitions *)
fun name nm = map_transition (fn (_, pos, int_only, print, no_timing, trans) =>
(nm, pos, int_only, print, no_timing, trans));
fun position pos = map_transition (fn (name, _, int_only, print, no_timing, trans) =>
(name, pos, int_only, print, no_timing, trans));
fun interactive int_only = map_transition (fn (name, pos, _, print, no_timing, trans) =>
(name, pos, int_only, print, no_timing, trans));
val no_timing = map_transition (fn (name, pos, int_only, print, _, trans) =>
(name, pos, int_only, print, true, trans));
fun add_trans tr = map_transition (fn (name, pos, int_only, print, no_timing, trans) =>
(name, pos, int_only, print, no_timing, trans @ [tr]));
val print = map_transition (fn (name, pos, int_only, _, no_timing, trans) =>
(name, pos, int_only, true, no_timing, trans));
(* basic transitions *)
fun init_theory f exit kill = add_trans (Init (f, (exit, kill)));
fun init_empty check f = add_trans (InitEmpty (check, f));
val exit = add_trans Exit;
val undo_exit = add_trans UndoExit;
val kill = add_trans Kill;
val history = add_trans o History;
val keep' = add_trans o Keep;
fun map_current f = add_trans (Transaction (false, f));
fun app_current f = add_trans (Transaction (true, f));
fun keep f = add_trans (Keep (fn _ => f));
fun imperative f = keep (fn _ => f ());
val unknown_theory = imperative (fn () => warning "Unknown theory context");
val unknown_proof = imperative (fn () => warning "Unknown proof context");
val unknown_context = imperative (fn () => warning "Unknown context");
(* theory transitions *)
fun generic_theory f = app_current (fn _ =>
(fn Theory (gthy, _) => Theory (f gthy, NONE)
| _ => raise UNDEF));
fun theory' f = app_current (fn int =>
(fn Theory (Context.Theory thy, _) => Theory (Context.Theory (f int thy), NONE)
| _ => raise UNDEF));
fun theory f = theory' (K f);
fun begin_local_theory begin f = app_current (fn _ =>
(fn Theory (Context.Theory thy, _) =>
let
val lthy = f thy;
val gthy = if begin then Context.Proof lthy else Context.Theory (loc_exit lthy);
in Theory (gthy, SOME lthy) end
| _ => raise UNDEF));
val end_local_theory = app_current (fn _ =>
(fn Theory (Context.Proof lthy, _) => Theory (Context.Theory (loc_exit lthy), SOME lthy)
| _ => raise UNDEF));
local
fun local_theory_presentation loc f g = app_current (fn int =>
(fn Theory (gthy, _) =>
let
val finish = loc_finish loc gthy;
val lthy' = f (loc_begin loc gthy);
in Theory (finish lthy', SOME lthy') end
| _ => raise UNDEF) #> tap (g int));
in
fun local_theory loc f = local_theory_presentation loc f (K I);
fun present_local_theory loc g = local_theory_presentation loc I g;
end;
(* proof transitions *)
fun end_proof f = map_current (fn int =>
(fn Proof (prf, (finish, _)) =>
let val state = ProofHistory.current prf in
if can (Proof.assert_bottom true) state then
let
val ctxt' = f int state;
val gthy' = finish ctxt';
in Theory (gthy', SOME ctxt') end
else raise UNDEF
end
| SkipProof (h, (gthy, _)) =>
if History.current h = 0 then Theory (gthy, NONE) else raise UNDEF
| _ => raise UNDEF));
local
fun begin_proof init finish = app_current (fn int =>
(fn Theory (gthy, _) =>
let
val prf = init int gthy;
val schematic = Proof.schematic_goal prf;
in
if ! skip_proofs andalso schematic then
warning "Cannot skip proof of schematic goal statement"
else ();
if ! skip_proofs andalso not schematic then
SkipProof
(History.init (undo_limit int) 0, (finish gthy (Proof.global_skip_proof int prf), gthy))
else Proof (ProofHistory.init (undo_limit int) prf, (finish gthy, gthy))
end
| _ => raise UNDEF));
in
fun local_theory_to_proof' loc f = begin_proof
(fn int => fn gthy => f int (loc_begin loc gthy))
(loc_finish loc);
fun local_theory_to_proof loc f = local_theory_to_proof' loc (K f);
fun theory_to_proof f = begin_proof
(K (fn Context.Theory thy => f thy | _ => raise UNDEF))
(K (Context.Theory o ProofContext.theory_of));
end;
val forget_proof = map_current (fn _ =>
(fn Proof (_, (_, orig_gthy)) => Theory (orig_gthy, NONE)
| SkipProof (_, (_, orig_gthy)) => Theory (orig_gthy, NONE)
| _ => raise UNDEF));
fun present_proof f = map_current (fn int =>
(fn Proof (prf, x) => Proof (ProofHistory.apply I prf, x)
| SkipProof (h, x) => SkipProof (History.apply I h, x)
| _ => raise UNDEF) #> tap (f int));
fun proofs' f = map_current (fn int =>
(fn Proof (prf, x) => Proof (ProofHistory.applys (f int) prf, x)
| SkipProof (h, x) => SkipProof (History.apply I h, x)
| _ => raise UNDEF));
fun proof' f = proofs' (Seq.single oo f);
val proofs = proofs' o K;
val proof = proof' o K;
fun actual_proof f = map_current (fn _ =>
(fn Proof (prf, x) => Proof (f prf, x)
| _ => raise UNDEF));
fun skip_proof f = map_current (fn _ =>
(fn SkipProof (h, x) => SkipProof (f h, x)
| _ => raise UNDEF));
fun skip_proof_to_theory p = map_current (fn _ =>
(fn SkipProof (h, (gthy, _)) =>
if p (History.current h) then Theory (gthy, NONE)
else raise UNDEF
| _ => raise UNDEF));
(** toplevel transactions **)
(* thread position *)
fun setmp_thread_position (Transition {pos, ...}) f x =
Position.setmp_thread_data pos f x;
fun error_msg tr exn_info =
setmp_thread_position tr (fn () => Output.error_msg (exn_message (EXCURSION_FAIL exn_info))) ();
(* apply transitions *)
local
fun app int (tr as Transition {trans, pos, int_only, print, no_timing, ...}) =
setmp_thread_position tr (fn state =>
let
val _ = if not int andalso int_only then warning (command_msg "Interactive-only " tr) else ();
fun do_timing f x = (warning (command_msg "" tr); timeap f x);
fun do_profiling f x = profile (! profiling) f x;
val (result, status) =
state |> (apply_trans int pos trans
|> (if ! profiling > 0 andalso not no_timing then do_profiling else I)
|> (if ! profiling > 0 orelse ! timing andalso not no_timing then do_timing else I));
val _ = if int andalso not (! quiet) andalso print then print_state false result else ();
in (result, Option.map (fn UNDEF => type_error tr state | exn => exn) status) end);
in
fun transition int tr st =
let val ctxt = try context_of st in
(case app int tr st of
(_, SOME TERMINATE) => NONE
| (_, SOME RESTART) => SOME (toplevel, NONE)
| (state', SOME (EXCURSION_FAIL exn_info)) => SOME (state', SOME exn_info)
| (state', SOME exn) => SOME (state', SOME (exn_context ctxt exn, at_command tr))
| (state', NONE) => SOME (state', NONE))
end;
end;
(* excursion: toplevel -- apply transformers/presentation -- toplevel *)
local
fun excur [] x = x
| excur ((tr, pr) :: trs) (st, res) =
(case transition (! interact) tr st of
SOME (st', NONE) =>
excur trs (st', pr st st' res handle exn =>
raise EXCURSION_FAIL (exn, "Presentation failed\n" ^ at_command tr))
| SOME (st', SOME exn_info) => raise EXCURSION_FAIL exn_info
| NONE => raise EXCURSION_FAIL (TERMINATE, at_command tr));
fun no_pr _ _ _ = ();
in
fun present_excursion trs res =
(case excur trs (toplevel, res) of
(state as Toplevel _, res') => (safe_exit state; res')
| _ => error "Unfinished development at end of input")
handle exn => error (exn_message exn);
fun excursion trs = present_excursion (map (rpair no_pr) trs) ();
end;
end;