module Ref = NReference
module E = NCicEnvironment
+exception AssertFailure of string Lazy.t;;
+
+let debug = ref false;;
+let pp m = if !debug then prerr_endline (Lazy.force m) else ();;
+
module type Strategy = sig
type stack_term
type env_term
type config = int * env_term list * C.term * stack_term list
val to_env :
- reduce: (config -> config * bool) -> unwind: (config -> C.term) ->
+ reduce: (delta:int -> config -> config * bool) ->
+ unwind: (config -> C.term) ->
config -> env_term
- val from_stack : stack_term -> config
+ val from_stack : delta:int -> stack_term -> config
val from_stack_list_for_unwind :
- unwind: (config -> C.term) -> stack_term list -> C.term list
- val from_env : env_term -> config
+ unwind: (config -> C.term) -> stack_term list -> C.term list
+ val from_env : delta:int -> env_term -> config
val from_env_for_unwind :
- unwind: (config -> C.term) -> env_term -> C.term
+ unwind: (config -> C.term) -> env_term -> C.term
val stack_to_env :
- reduce: (config -> config * bool) -> unwind: (config -> C.term) ->
+ reduce: (delta:int -> config -> config * bool) ->
+ unwind: (config -> C.term) ->
stack_term -> env_term
val compute_to_env :
- reduce: (config -> config * bool) -> unwind: (config -> C.term) ->
+ reduce: (delta:int -> config -> config * bool) ->
+ unwind: (config -> C.term) ->
int -> env_term list -> C.term -> env_term
val compute_to_stack :
- reduce: (config -> config * bool) -> unwind: (config -> C.term) ->
+ reduce: (delta:int -> config -> config * bool) ->
+ unwind: (config -> C.term) ->
config -> stack_term
end
;;
-module CallByValueByNameForUnwind' = struct
+module CallByValueByNameForUnwind' : Strategy = struct
type config = int * env_term list * C.term * stack_term list
- and stack_term = config lazy_t * C.term lazy_t (* cbv, cbn *)
- and env_term = config lazy_t * C.term lazy_t (* cbv, cbn *)
- let to_env ~reduce ~unwind c = lazy (fst (reduce c)),lazy (unwind c)
- let from_stack (c,_) = Lazy.force c
+ and stack_term =
+ config Lazy.t * (int -> config) * C.term Lazy.t
+ and env_term =
+ config Lazy.t (* cbneed ~delta:0 *)
+ * (int -> config) (* cbvalue ~delta *)
+ * C.term Lazy.t (* cbname ~delta:max_int *)
+ let to_env ~reduce ~unwind c =
+ lazy (fst (reduce ~delta:0 c)),
+ (fun delta -> fst (reduce ~delta c)),
+ lazy (unwind c)
+ let from_stack ~delta (c0,c,_) = if delta = 0 then Lazy.force c0 else c delta
let from_stack_list_for_unwind ~unwind:_ l =
- List.map (function (_,c) -> Lazy.force c) l
- let from_env (c,_) = Lazy.force c
- let from_env_for_unwind ~unwind:_ (_,c) = Lazy.force c
+ List.map (fun (_,_,c) -> Lazy.force c) l
+ let from_env ~delta (c0,c,_) = if delta = 0 then Lazy.force c0 else c delta
+ let from_env_for_unwind ~unwind:_ (_,_,c) = Lazy.force c
let stack_to_env ~reduce:_ ~unwind:_ config = config
let compute_to_env ~reduce ~unwind k e t =
- lazy (fst (reduce (k,e,t,[]))), lazy (unwind (k,e,t,[]))
+ lazy (fst (reduce ~delta:0 (k,e,t,[]))),
+ (fun delta -> fst (reduce ~delta (k,e,t,[]))),
+ lazy (unwind (k,e,t,[]))
let compute_to_stack ~reduce ~unwind config =
- lazy (fst (reduce config)), lazy (unwind config)
+ lazy (fst (reduce ~delta:0 config)),
+ (fun delta -> fst (reduce ~delta config)),
+ lazy (unwind config)
end
;;
let rec reduce ~delta ?(subst = []) context : config -> config * bool =
let rec aux = function
| k, e, C.Rel n, s when n <= k ->
- let k',e',t',s' = RS.from_env (list_nth e (n-1)) in
+ let k',e',t',s' = RS.from_env ~delta (list_nth e (n-1)) in
aux (k',e',t',s'@s)
| k, _, C.Rel n, s as config (* when n > k *) ->
let x= try Some (List.nth context (n - 1 - k)) with Failure _ -> None in
| (_, _, C.Prod _, _)
| (_, _, C.Lambda _, []) as config -> config, true
| (k, e, C.Lambda (_,_,t), p::s) ->
- aux (k+1, (RS.stack_to_env ~reduce:aux ~unwind p)::e, t,s)
+ aux (k+1, (RS.stack_to_env ~reduce:(reduce ~subst context) ~unwind p)::e, t,s)
| (k, e, C.LetIn (_,_,m,t), s) ->
- let m' = RS.compute_to_env ~reduce:aux ~unwind k e m in
+ let m' = RS.compute_to_env ~reduce:(reduce ~subst context) ~unwind k e m in
aux (k+1, m'::e, t, s)
| (_, _, C.Appl ([]|[_]), _) -> assert false
| (k, e, C.Appl (he::tl), s) ->
let tl' =
- List.map (fun t->RS.compute_to_stack ~reduce:aux ~unwind (k,e,t,[])) tl
+ List.map (fun t->RS.compute_to_stack
+ ~reduce:(reduce ~subst context) ~unwind (k,e,t,[])) tl
in
aux (k, e, he, tl' @ s)
| (_, _, C.Const
(Ref.Ref (_,Ref.Def height) as refer), s) as config ->
- if delta >= height then config, false else
+ if delta >= height then
+ config, false
+ else
let _,_,body,_,_,_ = NCicEnvironment.get_checked_def refer in
aux (0, [], body, s)
| (_, _, C.Const (Ref.Ref (_,
(Ref.Decl|Ref.Ind _|Ref.Con _|Ref.CoFix _))), _) as config ->
config, true
| (_, _, (C.Const (Ref.Ref
- (_,Ref.Fix (fixno,recindex,height)) as refer) as head),s) as config ->
-(* if delta >= height then config else *)
- (match
- try Some (RS.from_stack (List.nth s recindex))
- with Failure _ -> None
- with
- | None -> config, true
- | Some recparam ->
- let fixes,_,_ = NCicEnvironment.get_checked_fixes_or_cofixes refer in
- match reduce ~delta:0 ~subst context recparam with
- | (_,_,C.Const (Ref.Ref (_,Ref.Con _)), _) as c, _
- when delta >= height ->
- let new_s =
- replace recindex s (RS.compute_to_stack ~reduce:aux ~unwind c)
- in
- (0, [], head, new_s), false
- | (_,_,C.Const (Ref.Ref (_,Ref.Con _)), _) as c, _ ->
- let new_s =
- replace recindex s (RS.compute_to_stack ~reduce:aux ~unwind c)
- in
- let _,_,_,_,body = List.nth fixes fixno in
- aux (0, [], body, new_s)
- | _ -> config, true)
+ (_,Ref.Fix (fixno,recindex,height)) as refer)),s) as config ->
+ (let arg = try Some (List.nth s recindex) with Failure _ -> None in
+ match arg with
+ None -> config, true
+ | Some arg ->
+ let fixes,(_,_,pragma),_ =
+ NCicEnvironment.get_checked_fixes_or_cofixes refer in
+ if delta >= height then
+ match pragma with
+ | `Projection ->
+ (match RS.from_stack ~delta:max_int arg with
+ | _,_,C.Const(Ref.Ref(_,Ref.Con _)),_::_ ->
+ let _,_,_,_,body = List.nth fixes fixno in
+ aux (0, [], body, s)
+ | _ -> config,false)
+ | _ -> config,false
+ else
+ match RS.from_stack ~delta:0 arg with
+ | (_,_,C.Const (Ref.Ref (_,Ref.Con _)), _) as c ->
+ let new_s =
+ replace recindex s
+ (RS.compute_to_stack ~reduce:(reduce ~subst context)
+ ~unwind c) in
+ let _,_,_,_,body = List.nth fixes fixno in
+ aux (0, [], body, new_s)
+ | _ -> config, true)
| (k, e, C.Match (_,_,term,pl),s) as config ->
let decofix = function
| (_,_,C.Const(Ref.Ref(_,Ref.CoFix c)as refer),s)->
c
| config -> config
in
- (match decofix (fst (reduce ~delta:0 ~subst context (k,e,term,[]))) with
+ let match_head = k,e,term,[] in
+ let reduced,_ = reduce ~delta:0 ~subst context match_head in
+ (match decofix reduced with
| (_, _, C.Const (Ref.Ref (_,Ref.Con (_,j,_))),[]) ->
aux (k, e, List.nth pl (j-1), s)
| (_, _, C.Const (Ref.Ref (_,Ref.Con (_,j,lno))), s')->
let _,params = HExtlib.split_nth lno s' in
aux (k, e, List.nth pl (j-1), params@s)
- | _ -> config,true)
+ | _ -> config, true)
in
aux
;;
let set_get_relevance f = get_relevance := f;;
+let alpha_eq ~test_lambda_source aux test_eq_only metasenv subst context t1 t2 =
+ if t1 === t2 then
+ true
+ else
+ match (t1,t2) with
+ | C.Sort s1, C.Sort s2 ->
+ NCicEnvironment.are_sorts_convertible ~test_eq_only s1 s2
+
+ | (C.Prod (name1,s1,t1), C.Prod(_,s2,t2)) ->
+ aux true context s1 s2 &&
+ aux test_eq_only ((name1, C.Decl s1)::context) t1 t2
+ | (C.Lambda (name1,s1,t1), C.Lambda(_,_,t2)) ->
+ if test_lambda_source then
+ aux test_eq_only context t1 t2
+ else
+ (* thanks to inversion of well typedness, the source
+ * of these lambdas must be already convertible *)
+ aux test_eq_only ((name1, C.Decl s1)::context) t1 t2
+ | (C.LetIn (name1,ty1,s1,t1), C.LetIn(_,ty2,s2,t2)) ->
+ aux test_eq_only context ty1 ty2 &&
+ aux test_eq_only context s1 s2 &&
+ aux test_eq_only ((name1, C.Def (s1,ty1))::context) t1 t2
+
+ | (C.Meta (n1,(s1, C.Irl _)), C.Meta (n2,(s2, C.Irl _)))
+ when n1 = n2 && s1 = s2 -> true
+ | (C.Meta (n1,(s1, l1)), C.Meta (n2,(s2, l2))) when n1 = n2 &&
+ let l1 = NCicUtils.expand_local_context l1 in
+ let l2 = NCicUtils.expand_local_context l2 in
+ (try List.for_all2
+ (fun t1 t2 -> aux test_eq_only context
+ (NCicSubstitution.lift s1 t1)
+ (NCicSubstitution.lift s2 t2))
+ l1 l2
+ with Invalid_argument "List.for_all2" ->
+ prerr_endline ("Meta " ^ string_of_int n1 ^
+ " occurrs with local contexts of different lenght\n"^
+ NCicPp.ppterm ~metasenv ~subst ~context t1 ^ " === " ^
+ NCicPp.ppterm ~metasenv ~subst ~context t2);
+ assert false) -> true
+
+ | C.Meta (n1,l1), _ ->
+ (try
+ let _,_,term,_ = NCicUtils.lookup_subst n1 subst in
+ let term = NCicSubstitution.subst_meta l1 term in
+ aux test_eq_only context term t2
+ with NCicUtils.Subst_not_found _ -> false)
+ | _, C.Meta (n2,l2) ->
+ (try
+ let _,_,term,_ = NCicUtils.lookup_subst n2 subst in
+ let term = NCicSubstitution.subst_meta l2 term in
+ aux test_eq_only context t1 term
+ with NCicUtils.Subst_not_found _ -> false)
+
+ | (C.Appl ((C.Const r1) as hd1::tl1), C.Appl (C.Const r2::tl2))
+ when (Ref.eq r1 r2 &&
+ List.length (E.get_relevance r1) >= List.length tl1) ->
+ let relevance = E.get_relevance r1 in
+ let relevance = match r1 with
+ | Ref.Ref (_,Ref.Con (_,_,lno)) ->
+ let _,relevance = HExtlib.split_nth lno relevance in
+ HExtlib.mk_list false lno @ relevance
+ | _ -> relevance
+ in
+ (try
+ HExtlib.list_forall_default3_var
+ (fun t1 t2 b -> not b || aux true context t1 t2 )
+ tl1 tl2 true relevance
+ with Invalid_argument _ -> false
+ | HExtlib.FailureAt fail ->
+ let relevance =
+ !get_relevance ~metasenv ~subst context hd1 tl1 in
+ let _,relevance = HExtlib.split_nth fail relevance in
+ let b,relevance = (match relevance with
+ | [] -> assert false
+ | b::tl -> b,tl) in
+ if (not b) then
+ let _,tl1 = HExtlib.split_nth (fail+1) tl1 in
+ let _,tl2 = HExtlib.split_nth (fail+1) tl2 in
+ try
+ HExtlib.list_forall_default3
+ (fun t1 t2 b -> not b || aux true context t1 t2)
+ tl1 tl2 true relevance
+ with Invalid_argument _ -> false
+ else false)
+
+ | (C.Appl (hd1::tl1), C.Appl (hd2::tl2)) ->
+ aux test_eq_only context hd1 hd2 &&
+ let relevance = !get_relevance ~metasenv ~subst context hd1 tl1 in
+ (try
+ HExtlib.list_forall_default3
+ (fun t1 t2 b -> not b || aux true context t1 t2)
+ tl1 tl2 true relevance
+ with Invalid_argument _ -> false)
+
+ | (C.Match (Ref.Ref (_,Ref.Ind (_,tyno,_)) as ref1,outtype1,term1,pl1),
+ C.Match (ref2,outtype2,term2,pl2)) ->
+ let _,_,itl,_,_ = E.get_checked_indtys ref1 in
+ let _,_,ty,_ = List.nth itl tyno in
+ let rec remove_prods ~subst context ty =
+ let ty = whd ~subst context ty in
+ match ty with
+ | C.Sort _ -> ty
+ | C.Prod (name,so,ta) -> remove_prods ~subst ((name,(C.Decl so))::context) ta
+ | _ -> assert false
+ in
+ let is_prop =
+ match remove_prods ~subst [] ty with
+ | C.Sort C.Prop -> true
+ | _ -> false
+ in
+ Ref.eq ref1 ref2 &&
+ aux test_eq_only context outtype1 outtype2 &&
+ (is_prop || aux test_eq_only context term1 term2) &&
+ (try List.for_all2 (aux test_eq_only context) pl1 pl2
+ with Invalid_argument _ -> false)
+ | (C.Implicit _, _) | (_, C.Implicit _) -> assert false
+ | (_,_) -> false
+;;
+
(* t1, t2 must be well-typed *)
let are_convertible ~metasenv ~subst =
let rec aux test_eq_only context t1 t2 =
- let alpha_eq test_eq_only t1 t2 =
- if t1 === t2 then
- true
- else
- match (t1,t2) with
- | (C.Sort (C.Type a), C.Sort (C.Type b)) when not test_eq_only ->
- NCicEnvironment.universe_leq a b
- | (C.Sort (C.Type a), C.Sort (C.Type b)) ->
- NCicEnvironment.universe_eq a b
- | (C.Sort C.Prop,C.Sort (C.Type _)) -> (not test_eq_only)
- | (C.Sort C.Prop, C.Sort C.Prop) -> true
-
- | (C.Prod (name1,s1,t1), C.Prod(_,s2,t2)) ->
- aux true context s1 s2 &&
- aux test_eq_only ((name1, C.Decl s1)::context) t1 t2
- | (C.Lambda (name1,s1,t1), C.Lambda(_,_,t2)) ->
- (* thanks to inversion of well typedness, the source
- * of these lambdas must be already convertible *)
- aux test_eq_only ((name1, C.Decl s1)::context) t1 t2
- | (C.LetIn (name1,ty1,s1,t1), C.LetIn(_,ty2,s2,t2)) ->
- aux test_eq_only context ty1 ty2 &&
- aux test_eq_only context s1 s2 &&
- aux test_eq_only ((name1, C.Def (s1,ty1))::context) t1 t2
-
- | (C.Meta (n1,(s1, C.Irl _)), C.Meta (n2,(s2, C.Irl _)))
- when n1 = n2 && s1 = s2 -> true
- | (C.Meta (n1,(s1, l1)), C.Meta (n2,(s2, l2))) when n1 = n2 &&
- let l1 = NCicUtils.expand_local_context l1 in
- let l2 = NCicUtils.expand_local_context l2 in
- (try List.for_all2
- (fun t1 t2 -> aux test_eq_only context
- (NCicSubstitution.lift s1 t1)
- (NCicSubstitution.lift s2 t2))
- l1 l2
- with Invalid_argument "List.for_all2" ->
- prerr_endline ("Meta " ^ string_of_int n1 ^
- " occurrs with local contexts of different lenght\n"^
- NCicPp.ppterm ~metasenv ~subst ~context t1 ^ " === " ^
- NCicPp.ppterm ~metasenv ~subst ~context t2);
- assert false) -> true
-
- | C.Meta (n1,l1), _ ->
- (try
- let _,_,term,_ = NCicUtils.lookup_subst n1 subst in
- let term = NCicSubstitution.subst_meta l1 term in
- aux test_eq_only context term t2
- with NCicUtils.Subst_not_found _ -> false)
- | _, C.Meta (n2,l2) ->
- (try
- let _,_,term,_ = NCicUtils.lookup_subst n2 subst in
- let term = NCicSubstitution.subst_meta l2 term in
- aux test_eq_only context t1 term
- with NCicUtils.Subst_not_found _ -> false)
-
- | (C.Appl ((C.Const r1) as hd1::tl1), C.Appl (C.Const r2::tl2))
- when (Ref.eq r1 r2 &&
- List.length (E.get_relevance r1) >= List.length tl1) ->
- let relevance = E.get_relevance r1 in
- let relevance = match r1 with
- | Ref.Ref (_,Ref.Con (_,_,lno)) ->
- let _,relevance = HExtlib.split_nth lno relevance in
- HExtlib.mk_list false lno @ relevance
- | _ -> relevance
- in
- (try
- HExtlib.list_forall_default3_var
- (fun t1 t2 b -> not b || aux test_eq_only context t1 t2 )
- tl1 tl2 true relevance
- with Invalid_argument _ -> false
- | HExtlib.FailureAt fail ->
- let relevance =
- !get_relevance ~metasenv ~subst context hd1 tl1 in
- let _,relevance = HExtlib.split_nth fail relevance in
- let b,relevance = (match relevance with
- | [] -> assert false
- | b::tl -> b,tl) in
- if (not b) then
- let _,tl1 = HExtlib.split_nth (fail+1) tl1 in
- let _,tl2 = HExtlib.split_nth (fail+1) tl2 in
- try
- HExtlib.list_forall_default3
- (fun t1 t2 b -> not b || aux test_eq_only context t1 t2)
- tl1 tl2 true relevance
- with Invalid_argument _ -> false
- else false)
-
- | (C.Appl (hd1::tl1), C.Appl (hd2::tl2)) ->
- aux test_eq_only context hd1 hd2 &&
- let relevance = !get_relevance ~metasenv ~subst context hd1 tl1 in
- (try
- HExtlib.list_forall_default3
- (fun t1 t2 b -> not b || aux test_eq_only context t1 t2)
- tl1 tl2 true relevance
- with Invalid_argument _ -> false)
-
- | (C.Match (Ref.Ref (_,Ref.Ind (_,tyno,_)) as ref1,outtype1,term1,pl1),
- C.Match (ref2,outtype2,term2,pl2)) ->
- let _,_,itl,_,_ = E.get_checked_indtys ref1 in
- let _,_,ty,_ = List.nth itl tyno in
- let rec remove_prods ~subst context ty =
- let ty = whd ~subst context ty in
- match ty with
- | C.Sort _ -> ty
- | C.Prod (name,so,ta) -> remove_prods ~subst ((name,(C.Decl so))::context) ta
- | _ -> assert false
- in
- let is_prop =
- match remove_prods ~subst [] ty with
- | C.Sort C.Prop -> true
- | _ -> false
- in
- Ref.eq ref1 ref2 &&
- aux test_eq_only context outtype1 outtype2 &&
- (is_prop || aux test_eq_only context term1 term2) &&
- (try List.for_all2 (aux test_eq_only context) pl1 pl2
- with Invalid_argument _ -> false)
- | (C.Implicit _, _) | (_, C.Implicit _) -> assert false
- | (_,_) -> false
+ let alpha_eq test_eq_only =
+ alpha_eq ~test_lambda_source:false aux test_eq_only metasenv subst context
in
if alpha_eq test_eq_only t1 t2 then
true
R.reduce ~delta ~subst context m1,
R.reduce ~delta ~subst context m2
in
- let rec convert_machines
+ let rec convert_machines test_eq_only
((k1,e1,t1,s1),norm1 as m1),((k2,e2,t2,s2), norm2 as m2)
=
(alpha_eq test_eq_only
HExtlib.list_forall_default3
(fun t1 t2 b ->
not b ||
- let t1 = RS.from_stack t1 in
- let t2 = RS.from_stack t2 in
- convert_machines (put_in_whd t1 t2)) s1 s2 true relevance
+ let t1 = RS.from_stack ~delta:max_int t1 in
+ let t2 = RS.from_stack ~delta:max_int t2 in
+ convert_machines true (put_in_whd t1 t2)) s1 s2 true relevance
with Invalid_argument _ -> false) ||
- (not (norm1 && norm2) && convert_machines (small_delta_step m1 m2))
+ (not (norm1 && norm2) && convert_machines test_eq_only (small_delta_step m1 m2))
in
- convert_machines (put_in_whd (0,[],t1,[]) (0,[],t2,[]))
+ convert_machines test_eq_only (put_in_whd (0,[],t1,[]) (0,[],t2,[]))
in
aux false
;;
-let rec head_beta_reduce ?(delta=max_int) ?(upto=(-1)) t l =
+let alpha_eq metasenv subst =
+ let rec aux test_lambda_source context t1 t2 =
+ alpha_eq ~test_lambda_source aux true metasenv subst context t1 t2
+ in
+ aux true
+;;
+
+let rec head_beta_reduce ~delta ~upto ~subst t l =
match upto, t, l with
| 0, C.Appl l1, _ -> C.Appl (l1 @ l)
| 0, t, [] -> t
| 0, t, _ -> C.Appl (t::l)
- | _, C.Appl (hd::tl), _ -> head_beta_reduce ~delta ~upto hd (tl @ l)
+ | _, C.Meta (n,ctx), _ ->
+ (try
+ let _,_, term,_ = NCicUtils.lookup_subst n subst in
+ head_beta_reduce ~delta ~upto ~subst
+ (NCicSubstitution.subst_meta ctx term) l
+ with NCicUtils.Subst_not_found _ -> if l = [] then t else C.Appl (t::l))
+ | _, C.Appl (hd::tl), _ -> head_beta_reduce ~delta ~upto ~subst hd (tl @ l)
| _, C.Lambda(_,_,bo), arg::tl ->
let bo = NCicSubstitution.subst arg bo in
- head_beta_reduce ~delta ~upto:(upto - 1) bo tl
+ head_beta_reduce ~delta ~upto:(upto - 1) ~subst bo tl
| _, C.Const (Ref.Ref (_, Ref.Def height) as re), _
when delta <= height ->
let _, _, bo, _, _, _ = NCicEnvironment.get_checked_def re in
- head_beta_reduce ~upto ~delta bo l
+ head_beta_reduce ~upto ~delta ~subst bo l
| _, t, [] -> t
| _, t, _ -> C.Appl (t::l)
;;
-let head_beta_reduce ?delta ?upto t = head_beta_reduce ?delta ?upto t [];;
+let head_beta_reduce ?(delta=max_int) ?(upto= -1) ?(subst=[]) t =
+ head_beta_reduce ~delta ~upto ~subst t []
+;;
type stack_item = RS.stack_term
type environment_item = RS.env_term
let from_stack = RS.from_stack
let unwind = R.unwind
+let _ =
+ NCicUtils.set_head_beta_reduce (fun ~upto t -> head_beta_reduce ~upto t);
+ NCicPp.set_head_beta_reduce (fun ~upto t -> head_beta_reduce ~upto t);
+;;
+
+(* if n < 0, then splits all prods from an arity, returning a sort *)
+let rec split_prods ~subst context n te =
+ match (n, R.whd ~subst context te) with
+ | (0, _) -> context,te
+ | (n, C.Sort _) when n <= 0 -> context,te
+ | (n, C.Prod (name,so,ta)) ->
+ split_prods ~subst ((name,(C.Decl so))::context) (n - 1) ta
+ | (_, _) -> raise (AssertFailure (lazy "split_prods"))
+;;
+
(* vim:set foldmethod=marker: *)