(************************************************************************)
(* v * The Coq Proof Assistant / The Coq Development Team *)
(* <O___,, * CNRS-Ecole Polytechnique-INRIA Futurs-Universite Paris Sud *)
(* \VV/ **************************************************************)
(* // * This file is distributed under the terms of the *)
(* * GNU Lesser General Public License Version 2.1 *)
(************************************************************************)
(* $Id: inductive.ml 11647 2008-12-02 10:40:11Z barras $ *)
open Util
open Names
open Univ
open Term
open Sign
open Declarations
open Environ
open Reduction
open Type_errors
type mind_specif = mutual_inductive_body * one_inductive_body
(* raise Not_found if not an inductive type *)
let lookup_mind_specif env (kn,tyi) =
let mib = Environ.lookup_mind kn env in
if tyi >= Array.length mib.mind_packets then
error "Inductive.lookup_mind_specif: invalid inductive index";
(mib, mib.mind_packets.(tyi))
let find_rectype env c =
let (t, l) = decompose_app (whd_betadeltaiota env c) in
match kind_of_term t with
| Ind ind -> (ind, l)
| _ -> raise Not_found
let find_inductive env c =
let (t, l) = decompose_app (whd_betadeltaiota env c) in
match kind_of_term t with
| Ind ind
when (fst (lookup_mind_specif env ind)).mind_finite -> (ind, l)
| _ -> raise Not_found
let find_coinductive env c =
let (t, l) = decompose_app (whd_betadeltaiota env c) in
match kind_of_term t with
| Ind ind
when not (fst (lookup_mind_specif env ind)).mind_finite -> (ind, l)
| _ -> raise Not_found
let inductive_params (mib,_) = mib.mind_nparams
(************************************************************************)
(* Build the substitution that replaces Rels by the appropriate *)
(* inductives *)
let ind_subst mind mib =
let ntypes = mib.mind_ntypes in
let make_Ik k = mkInd (mind,ntypes-k-1) in
list_tabulate make_Ik ntypes
(* Instantiate inductives in constructor type *)
let constructor_instantiate mind mib c =
let s = ind_subst mind mib in
substl s c
let instantiate_params full t args sign =
let fail () =
anomaly "instantiate_params: type, ctxt and args mismatch" in
let (rem_args, subs, ty) =
Sign.fold_rel_context
(fun (_,copt,_) (largs,subs,ty) ->
match (copt, largs, kind_of_term ty) with
| (None, a::args, Prod(_,_,t)) -> (args, a::subs, t)
| (Some b,_,LetIn(_,_,_,t)) -> (largs, (substl subs b)::subs, t)
| (_,[],_) -> if full then fail() else ([], subs, ty)
| _ -> fail ())
sign
~init:(args,[],t)
in
if rem_args <> [] then fail();
substl subs ty
let instantiate_partial_params = instantiate_params false
let full_inductive_instantiate mib params sign =
let dummy = prop_sort in
let t = mkArity (sign,dummy) in
fst (destArity (instantiate_params true t params mib.mind_params_ctxt))
let full_constructor_instantiate ((mind,_),(mib,_),params) =
let inst_ind = constructor_instantiate mind mib in
(fun t ->
instantiate_params true (inst_ind t) params mib.mind_params_ctxt)
(************************************************************************)
(************************************************************************)
(* Functions to build standard types related to inductive *)
let number_of_inductives mib = Array.length mib.mind_packets
let number_of_constructors mip = Array.length mip.mind_consnames
(*
Computing the actual sort of an applied or partially applied inductive type:
I_i: forall uniformparams:utyps, forall otherparams:otyps, Type(a)
uniformargs : utyps
otherargs : otyps
I_1:forall ...,s_1;...I_n:forall ...,s_n |- sort(C_kj(uniformargs)) = s_kj
s'_k = max(..s_kj..)
merge(..s'_k..) = ..s''_k..
--------------------------------------------------------------------
Gamma |- I_i uniformargs otherargs : phi(s''_i)
where
- if p=0, phi() = Prop
- if p=1, phi(s) = s
- if p<>1, phi(s) = sup(Set,s)
Remark: Set (predicative) is encoded as Type(0)
*)
let sort_as_univ = function
| Type u -> u
| Prop Null -> type0m_univ
| Prop Pos -> type0_univ
let cons_subst u su subst =
try (u, sup su (List.assoc u subst)) :: List.remove_assoc u subst
with Not_found -> (u, su) :: subst
let actualize_decl_level env lev t =
let sign,s = dest_arity env t in
mkArity (sign,lev)
let polymorphism_on_non_applied_parameters = false
(* Bind expected levels of parameters to actual levels *)
(* Propagate the new levels in the signature *)
let rec make_subst env = function
| (_,Some _,_ as t)::sign, exp, args ->
let ctx,subst = make_subst env (sign, exp, args) in
t::ctx, subst
| d::sign, None::exp, args ->
let args = match args with _::args -> args | [] -> [] in
let ctx,subst = make_subst env (sign, exp, args) in
d::ctx, subst
| d::sign, Some u::exp, a::args ->
(* We recover the level of the argument, but we don't change the *)
(* level in the corresponding type in the arity; this level in the *)
(* arity is a global level which, at typing time, will be enforce *)
(* to be greater than the level of the argument; this is probably *)
(* a useless extra constraint *)
let s = sort_as_univ (snd (dest_arity env a)) in
let ctx,subst = make_subst env (sign, exp, args) in
d::ctx, cons_subst u s subst
| (na,None,t as d)::sign, Some u::exp, [] ->
(* No more argument here: we instantiate the type with a fresh level *)
(* which is first propagated to the corresponding premise in the arity *)
(* (actualize_decl_level), then to the conclusion of the arity (via *)
(* the substitution) *)
let ctx,subst = make_subst env (sign, exp, []) in
if polymorphism_on_non_applied_parameters then
let s = fresh_local_univ () in
let t = actualize_decl_level env (Type s) t in
(na,None,t)::ctx, cons_subst u s subst
else
d::ctx, subst
| sign, [], _ ->
(* Uniform parameters are exhausted *)
sign,[]
| [], _, _ ->
assert false
let instantiate_universes env ctx ar argsorts =
let args = Array.to_list argsorts in
let ctx,subst = make_subst env (ctx,ar.poly_param_levels,args) in
let level = subst_large_constraints subst ar.poly_level in
ctx,
(* Singleton type not containing types are interpretable in Prop *)
if is_type0m_univ level then prop_sort
(* Non singleton type not containing types are interpretable in Set *)
else if is_type0_univ level then set_sort
(* This is a Type with constraints *)
else Type level
let type_of_inductive_knowing_parameters env mip paramtyps =
match mip.mind_arity with
| Monomorphic s ->
s.mind_user_arity
| Polymorphic ar ->
let ctx = List.rev mip.mind_arity_ctxt in
let ctx,s = instantiate_universes env ctx ar paramtyps in
mkArity (List.rev ctx,s)
(* Type of a (non applied) inductive type *)
let type_of_inductive env (_,mip) =
type_of_inductive_knowing_parameters env mip [||]
(* The max of an array of universes *)
let cumulate_constructor_univ u = function
| Prop Null -> u
| Prop Pos -> sup type0_univ u
| Type u' -> sup u u'
let max_inductive_sort =
Array.fold_left cumulate_constructor_univ type0m_univ
(************************************************************************)
(* Type of a constructor *)
let type_of_constructor cstr (mib,mip) =
let ind = inductive_of_constructor cstr in
let specif = mip.mind_user_lc in
let i = index_of_constructor cstr in
let nconstr = Array.length mip.mind_consnames in
if i > nconstr then error "Not enough constructors in the type.";
constructor_instantiate (fst ind) mib specif.(i-1)
let arities_of_specif kn (mib,mip) =
let specif = mip.mind_nf_lc in
Array.map (constructor_instantiate kn mib) specif
let arities_of_constructors ind specif =
arities_of_specif (fst ind) specif
let type_of_constructors ind (mib,mip) =
let specif = mip.mind_user_lc in
Array.map (constructor_instantiate (fst ind) mib) specif
(************************************************************************)
let error_elim_expln kp ki =
match kp,ki with
| (InType | InSet), InProp -> NonInformativeToInformative
| InType, InSet -> StrongEliminationOnNonSmallType (* if Set impredicative *)
| _ -> WrongArity
(* Type of case predicates *)
let local_rels ctxt =
let (rels,_) =
Sign.fold_rel_context_reverse
(fun (rels,n) (_,copt,_) ->
match copt with
None -> (mkRel n :: rels, n+1)
| Some _ -> (rels, n+1))
~init:([],1)
ctxt
in
rels
(* Get type of inductive, with parameters instantiated *)
let inductive_sort_family mip =
match mip.mind_arity with
| Monomorphic s -> family_of_sort s.mind_sort
| Polymorphic _ -> InType
let mind_arity mip =
mip.mind_arity_ctxt, inductive_sort_family mip
let get_instantiated_arity (mib,mip) params =
let sign, s = mind_arity mip in
full_inductive_instantiate mib params sign, s
let elim_sorts (_,mip) = mip.mind_kelim
let rel_list n m =
let rec reln l p =
if p>m then l else reln (mkRel(n+p)::l) (p+1)
in
reln [] 1
let build_dependent_inductive ind (_,mip) params =
let nrealargs = mip.mind_nrealargs in
applist
(mkInd ind, (List.map (lift nrealargs) params)@(rel_list 0 nrealargs))
(* This exception is local *)
exception LocalArity of (sorts_family * sorts_family * arity_error) option
let check_allowed_sort ksort specif =
if not (List.exists ((=) ksort) (elim_sorts specif)) then
let s = inductive_sort_family (snd specif) in
raise (LocalArity (Some(ksort,s,error_elim_expln ksort s)))
let is_correct_arity env c pj ind specif params =
let arsign,_ = get_instantiated_arity specif params in
let rec srec env pt ar u =
let pt' = whd_betadeltaiota env pt in
match kind_of_term pt', ar with
| Prod (na1,a1,t), (_,None,a1')::ar' ->
let univ =
try conv env a1 a1'
with NotConvertible -> raise (LocalArity None) in
srec (push_rel (na1,None,a1) env) t ar' (Constraint.union u univ)
| Prod (_,a1,a2), [] -> (* whnf of t was not needed here! *)
let ksort = match kind_of_term (whd_betadeltaiota env a2) with
| Sort s -> family_of_sort s
| _ -> raise (LocalArity None) in
let dep_ind = build_dependent_inductive ind specif params in
let univ =
try conv env a1 dep_ind
with NotConvertible -> raise (LocalArity None) in
check_allowed_sort ksort specif;
(true, Constraint.union u univ)
| Sort s', [] ->
check_allowed_sort (family_of_sort s') specif;
(false, u)
| _ ->
raise (LocalArity None)
in
try srec env pj.uj_type (List.rev arsign) Constraint.empty
with LocalArity kinds ->
error_elim_arity env ind (elim_sorts specif) c pj kinds
(************************************************************************)
(* Type of case branches *)
(* [p] is the predicate, [i] is the constructor number (starting from 0),
and [cty] is the type of the constructor (params not instantiated) *)
let build_branches_type ind (_,mip as specif) params dep p =
let build_one_branch i cty =
let typi = full_constructor_instantiate (ind,specif,params) cty in
let (args,ccl) = decompose_prod_assum typi in
let nargs = rel_context_length args in
let (_,allargs) = decompose_app ccl in
let (lparams,vargs) = list_chop (inductive_params specif) allargs in
let cargs =
if dep then
let cstr = ith_constructor_of_inductive ind (i+1) in
let dep_cstr = applist (mkConstruct cstr,lparams@(local_rels args)) in
vargs @ [dep_cstr]
else
vargs in
let base = beta_appvect (lift nargs p) (Array.of_list cargs) in
it_mkProd_or_LetIn base args in
Array.mapi build_one_branch mip.mind_nf_lc
(* [p] is the predicate, [c] is the match object, [realargs] is the
list of real args of the inductive type *)
let build_case_type dep p c realargs =
let args = if dep then realargs@[c] else realargs in
beta_appvect p (Array.of_list args)
let type_case_branches env (ind,largs) pj c =
let specif = lookup_mind_specif env ind in
let nparams = inductive_params specif in
let (params,realargs) = list_chop nparams largs in
let p = pj.uj_val in
let (dep,univ) = is_correct_arity env c pj ind specif params in
let lc = build_branches_type ind specif params dep p in
let ty = build_case_type dep p c realargs in
(lc, ty, univ)
(************************************************************************)
(* Checking the case annotation is relevent *)
let rec inductive_kn_equiv env kn1 kn2 =
match (lookup_mind kn1 env).mind_equiv with
| Some kn1' -> inductive_kn_equiv env kn2 kn1'
| None -> match (lookup_mind kn2 env).mind_equiv with
| Some kn2' -> inductive_kn_equiv env kn2' kn1
| None -> false
let inductive_equiv env (kn1,i1) (kn2,i2) =
i1=i2 & inductive_kn_equiv env kn1 kn2
let check_case_info env indsp ci =
let (mib,mip) = lookup_mind_specif env indsp in
if
not (Closure.mind_equiv env indsp ci.ci_ind) or
(mib.mind_nparams <> ci.ci_npar) or
(mip.mind_consnrealdecls <> ci.ci_cstr_nargs)
then raise (TypeError(env,WrongCaseInfo(indsp,ci)))
(************************************************************************)
(************************************************************************)
(* Guard conditions for fix and cofix-points *)
(* Check if t is a subterm of Rel n, and gives its specification,
assuming lst already gives index of
subterms with corresponding specifications of recursive arguments *)
(* A powerful notion of subterm *)
(* To each inductive definition corresponds an array describing the
structure of recursive arguments for each constructor, we call it
the recursive spec of the type (it has type recargs vect). For
checking the guard, we start from the decreasing argument (Rel n)
with its recursive spec. During checking the guardness condition,
we collect patterns variables corresponding to subterms of n, each
of them with its recursive spec. They are organised in a list lst
of type (int * recargs) list which is sorted with respect to the
first argument.
*)
(*************************************************************)
(* Environment annotated with marks on recursive arguments *)
(* tells whether it is a strict or loose subterm *)
type size = Large | Strict
(* merging information *)
let size_glb s1 s2 =
match s1,s2 with
Strict, Strict -> Strict
| _ -> Large
(* possible specifications for a term:
- Not_subterm: when the size of a term is not related to the
recursive argument of the fixpoint
- Subterm: when the term is a subterm of the recursive argument
the wf_paths argument specifies which subterms are recursive
- Dead_code: when the term has been built by elimination over an
empty type
*)
type subterm_spec =
Subterm of (size * wf_paths)
| Dead_code
| Not_subterm
let spec_of_tree t =
if Rtree.eq_rtree (=) t mk_norec then Not_subterm else Subterm(Strict,t)
let subterm_spec_glb =
let glb2 s1 s2 =
match s1,s2 with
_, Dead_code -> s1
| Dead_code, _ -> s2
| Not_subterm, _ -> Not_subterm
| _, Not_subterm -> Not_subterm
| Subterm (a1,t1), Subterm (a2,t2) ->
if Rtree.eq_rtree (=) t1 t2 then Subterm (size_glb a1 a2, t1)
(* branches do not return objects with same spec *)
else Not_subterm in
Array.fold_left glb2 Dead_code
type guard_env =
{ env : env;
(* dB of last fixpoint *)
rel_min : int;
(* inductive of recarg of each fixpoint *)
inds : inductive array;
(* the recarg information of inductive family *)
recvec : wf_paths array;
(* dB of variables denoting subterms *)
genv : subterm_spec list;
}
let make_renv env minds recarg (kn,tyi) =
let mib = Environ.lookup_mind kn env in
let mind_recvec =
Array.map (fun mip -> mip.mind_recargs) mib.mind_packets in
{ env = env;
rel_min = recarg+2;
inds = minds;
recvec = mind_recvec;
genv = [Subterm(Large,mind_recvec.(tyi))] }
let push_var renv (x,ty,spec) =
{ renv with
env = push_rel (x,None,ty) renv.env;
rel_min = renv.rel_min+1;
genv = spec:: renv.genv }
let assign_var_spec renv (i,spec) =
{ renv with genv = list_assign renv.genv (i-1) spec }
let push_var_renv renv (x,ty) =
push_var renv (x,ty,Not_subterm)
(* Fetch recursive information about a variable p *)
let subterm_var p renv =
try List.nth renv.genv (p-1)
with Failure _ | Invalid_argument _ -> Not_subterm
(* Add a variable and mark it as strictly smaller with information [spec]. *)
let add_subterm renv (x,a,spec) =
push_var renv (x,a,spec_of_tree spec)
let push_ctxt_renv renv ctxt =
let n = rel_context_length ctxt in
{ renv with
env = push_rel_context ctxt renv.env;
rel_min = renv.rel_min+n;
genv = iterate (fun ge -> Not_subterm::ge) n renv.genv }
let push_fix_renv renv (_,v,_ as recdef) =
let n = Array.length v in
{ renv with
env = push_rec_types recdef renv.env;
rel_min = renv.rel_min+n;
genv = iterate (fun ge -> Not_subterm::ge) n renv.genv }
(******************************)
(* Computing the recursive subterms of a term (propagation of size
information through Cases). *)
(*
c is a branch of an inductive definition corresponding to the spec
lrec. mind_recvec is the recursive spec of the inductive
definition of the decreasing argument n.
case_branches_specif renv lrec lc will pass the lambdas
of c corresponding to pattern variables and collect possibly new
subterms variables and returns the bodies of the branches with the
correct envs and decreasing args.
*)
let lookup_subterms env ind =
let (_,mip) = lookup_mind_specif env ind in
mip.mind_recargs
(*********************************)
(* Propagation of size information through Cases: if the matched
object is a recursive subterm then compute the information
associated to its own subterms.
Rq: if branch is not eta-long, then the recursive information
is not propagated to the missing abstractions *)
let case_branches_specif renv c_spec ind lbr =
let rec push_branch_args renv lrec c =
match lrec with
ra::lr ->
let c' = whd_betadeltaiota renv.env c in
(match kind_of_term c' with
Lambda(x,a,b) ->
let renv' = push_var renv (x,a,ra) in
push_branch_args renv' lr b
| _ -> (* branch not in eta-long form: cannot perform rec. calls *)
(renv,c'))
| [] -> (renv, c) in
match c_spec with
Subterm (_,t) ->
let sub_spec = Array.map (List.map spec_of_tree) (dest_subterms t) in
assert (Array.length sub_spec = Array.length lbr);
array_map2 (push_branch_args renv) sub_spec lbr
| Dead_code ->
let t = dest_subterms (lookup_subterms renv.env ind) in
let sub_spec = Array.map (List.map (fun _ -> Dead_code)) t in
assert (Array.length sub_spec = Array.length lbr);
array_map2 (push_branch_args renv) sub_spec lbr
| Not_subterm -> Array.map (fun c -> (renv,c)) lbr
(* [subterm_specif renv t] computes the recursive structure of [t] and
compare its size with the size of the initial recursive argument of
the fixpoint we are checking. [renv] collects such information
about variables.
*)
let rec subterm_specif renv t =
(* maybe reduction is not always necessary! *)
let f,l = decompose_app (whd_betadeltaiota renv.env t) in
match kind_of_term f with
| Rel k -> subterm_var k renv
| Case (ci,_,c,lbr) ->
if Array.length lbr = 0 then Dead_code
else
let c_spec = subterm_specif renv c in
let lbr_spec = case_branches_specif renv c_spec ci.ci_ind lbr in
let stl =
Array.map (fun (renv',br') -> subterm_specif renv' br')
lbr_spec in
subterm_spec_glb stl
| Fix ((recindxs,i),(_,typarray,bodies as recdef)) ->
(* when proving that the fixpoint f(x)=e is less than n, it is enough
to prove that e is less than n assuming f is less than n
furthermore when f is applied to a term which is strictly less than
n, one may assume that x itself is strictly less than n
*)
let (ctxt,clfix) = dest_prod renv.env typarray.(i) in
let oind =
let env' = push_rel_context ctxt renv.env in
try Some(fst(find_inductive env' clfix))
with Not_found -> None in
(match oind with
None -> Not_subterm (* happens if fix is polymorphic *)
| Some ind ->
let nbfix = Array.length typarray in
let recargs = lookup_subterms renv.env ind in
(* pushing the fixpoints *)
let renv' = push_fix_renv renv recdef in
let renv' =
(* Why Strict here ? To be general, it could also be
Large... *)
assign_var_spec renv' (nbfix-i, Subterm(Strict,recargs)) in
let decrArg = recindxs.(i) in
let theBody = bodies.(i) in
let nbOfAbst = decrArg+1 in
let sign,strippedBody = decompose_lam_n_assum nbOfAbst theBody in
(* pushing the fix parameters *)
let renv'' = push_ctxt_renv renv' sign in
let renv'' =
if List.length l < nbOfAbst then renv''
else
let theDecrArg = List.nth l decrArg in
let arg_spec = subterm_specif renv theDecrArg in
assign_var_spec renv'' (1, arg_spec) in
subterm_specif renv'' strippedBody)
| Lambda (x,a,b) ->
assert (l=[]);
subterm_specif (push_var_renv renv (x,a)) b
(* Metas and evars are considered OK *)
| (Meta _|Evar _) -> Dead_code
(* Other terms are not subterms *)
| _ -> Not_subterm
(* Check term c can be applied to one of the mutual fixpoints. *)
let check_is_subterm renv c =
match subterm_specif renv c with
Subterm (Strict,_) | Dead_code -> true
| _ -> false
(************************************************************************)
exception FixGuardError of env * guard_error
let error_illegal_rec_call renv fx arg =
let (_,le_vars,lt_vars) =
List.fold_left
(fun (i,le,lt) sbt ->
match sbt with
(Subterm(Strict,_) | Dead_code) -> (i+1, le, i::lt)
| (Subterm(Large,_)) -> (i+1, i::le, lt)
| _ -> (i+1, le ,lt))
(1,[],[]) renv.genv in
raise (FixGuardError (renv.env,
RecursionOnIllegalTerm(fx,arg,le_vars,lt_vars)))
let error_partial_apply renv fx =
raise (FixGuardError (renv.env,NotEnoughArgumentsForFixCall fx))
(* Check if [def] is a guarded fixpoint body with decreasing arg.
given [recpos], the decreasing arguments of each mutually defined
fixpoint. *)
let check_one_fix renv recpos def =
let nfi = Array.length recpos in
(* Checks if [t] only make valid recursive calls *)
let rec check_rec_call renv t =
(* if [t] does not make recursive calls, it is guarded: *)
if noccur_with_meta renv.rel_min nfi t then ()
else
let (f,l) = decompose_app (whd_betaiotazeta t) in
match kind_of_term f with
| Rel p ->
(* Test if [p] is a fixpoint (recursive call) *)
if renv.rel_min <= p & p < renv.rel_min+nfi then
begin
List.iter (check_rec_call renv) l;
(* the position of the invoked fixpoint: *)
let glob = renv.rel_min+nfi-1-p in
(* the decreasing arg of the rec call: *)
let np = recpos.(glob) in
if List.length l <= np then error_partial_apply renv glob
else
(* Check the decreasing arg is smaller *)
let z = List.nth l np in
if not (check_is_subterm renv z) then
error_illegal_rec_call renv glob z
end
else
begin
match pi2 (lookup_rel p renv.env) with
| None ->
List.iter (check_rec_call renv) l
| Some c ->
try List.iter (check_rec_call renv) l
with FixGuardError _ ->
check_rec_call renv (applist(lift p c,l))
end
| Case (ci,p,c_0,lrest) ->
List.iter (check_rec_call renv) (c_0::p::l);
(* compute the recarg information for the arguments of
each branch *)
let c_spec = subterm_specif renv c_0 in
let lbr = case_branches_specif renv c_spec ci.ci_ind lrest in
Array.iter (fun (renv',br') -> check_rec_call renv' br') lbr
(* Enables to traverse Fixpoint definitions in a more intelligent
way, ie, the rule :
if - g = Fix g/p := [y1:T1]...[yp:Tp]e &
- f is guarded with respect to the set of pattern variables S
in a1 ... am &
- f is guarded with respect to the set of pattern variables S
in T1 ... Tp &
- ap is a sub-term of the formal argument of f &
- f is guarded with respect to the set of pattern variables
S+{yp} in e
then f is guarded with respect to S in (g a1 ... am).
Eduardo 7/9/98 *)
| Fix ((recindxs,i),(_,typarray,bodies as recdef)) ->
List.iter (check_rec_call renv) l;
Array.iter (check_rec_call renv) typarray;
let decrArg = recindxs.(i) in
let renv' = push_fix_renv renv recdef in
if (List.length l < (decrArg+1)) then
Array.iter (check_rec_call renv') bodies
else
Array.iteri
(fun j body ->
if i=j then
let theDecrArg = List.nth l decrArg in
let arg_spec = subterm_specif renv theDecrArg in
check_nested_fix_body renv' (decrArg+1) arg_spec body
else check_rec_call renv' body)
bodies
| Const kn ->
if evaluable_constant kn renv.env then
try List.iter (check_rec_call renv) l
with (FixGuardError _ ) ->
check_rec_call renv(applist(constant_value renv.env kn, l))
else List.iter (check_rec_call renv) l
(* The cases below simply check recursively the condition on the
subterms *)
| Cast (a,_, b) ->
List.iter (check_rec_call renv) (a::b::l)
| Lambda (x,a,b) ->
List.iter (check_rec_call renv) (a::l);
check_rec_call (push_var_renv renv (x,a)) b
| Prod (x,a,b) ->
List.iter (check_rec_call renv) (a::l);
check_rec_call (push_var_renv renv (x,a)) b
| CoFix (i,(_,typarray,bodies as recdef)) ->
List.iter (check_rec_call renv) l;
Array.iter (check_rec_call renv) typarray;
let renv' = push_fix_renv renv recdef in
Array.iter (check_rec_call renv') bodies
| (Ind _ | Construct _ | Sort _) ->
List.iter (check_rec_call renv) l
| Var id ->
begin
match pi2 (lookup_named id renv.env) with
| None ->
List.iter (check_rec_call renv) l
| Some c ->
try List.iter (check_rec_call renv) l
with (FixGuardError _) -> check_rec_call renv (applist(c,l))
end
(* l is not checked because it is considered as the meta's context *)
| (Evar _ | Meta _) -> ()
| (App _ | LetIn _) -> assert false (* beta zeta reduction *)
and check_nested_fix_body renv decr recArgsDecrArg body =
if decr = 0 then
check_rec_call (assign_var_spec renv (1,recArgsDecrArg)) body
else
match kind_of_term body with
| Lambda (x,a,b) ->
check_rec_call renv a;
let renv' = push_var_renv renv (x,a) in
check_nested_fix_body renv' (decr-1) recArgsDecrArg b
| _ -> anomaly "Not enough abstractions in fix body"
in
check_rec_call renv def
let judgment_of_fixpoint (_, types, bodies) =
array_map2 (fun typ body -> { uj_val = body ; uj_type = typ }) types bodies
let inductive_of_mutfix env ((nvect,bodynum),(names,types,bodies as recdef)) =
let nbfix = Array.length bodies in
if nbfix = 0
or Array.length nvect <> nbfix
or Array.length types <> nbfix
or Array.length names <> nbfix
or bodynum < 0
or bodynum >= nbfix
then anomaly "Ill-formed fix term";
let fixenv = push_rec_types recdef env in
let vdefj = judgment_of_fixpoint recdef in
let raise_err env i err =
error_ill_formed_rec_body env err names i fixenv vdefj in
(* Check the i-th definition with recarg k *)
let find_ind i k def =
(* check fi does not appear in the k+1 first abstractions,
gives the type of the k+1-eme abstraction (must be an inductive) *)
let rec check_occur env n def =
match kind_of_term (whd_betadeltaiota env def) with
| Lambda (x,a,b) ->
if noccur_with_meta n nbfix a then
let env' = push_rel (x, None, a) env in
if n = k+1 then
(* get the inductive type of the fixpoint *)
let (mind, _) =
try find_inductive env a
with Not_found ->
raise_err env i (RecursionNotOnInductiveType a) in
(mind, (env', b))
else check_occur env' (n+1) b
else anomaly "check_one_fix: Bad occurrence of recursive call"
| _ -> raise_err env i NotEnoughAbstractionInFixBody in
check_occur fixenv 1 def in
(* Do it on every fixpoint *)
let rv = array_map2_i find_ind nvect bodies in
(Array.map fst rv, Array.map snd rv)
let check_fix env ((nvect,_),(names,_,bodies as recdef) as fix) =
let (minds, rdef) = inductive_of_mutfix env fix in
for i = 0 to Array.length bodies - 1 do
let (fenv,body) = rdef.(i) in
let renv = make_renv fenv minds nvect.(i) minds.(i) in
try check_one_fix renv nvect body
with FixGuardError (fixenv,err) ->
error_ill_formed_rec_body fixenv err names i
(push_rec_types recdef env) (judgment_of_fixpoint recdef)
done
(*
let cfkey = Profile.declare_profile "check_fix";;
let check_fix env fix = Profile.profile3 cfkey check_fix env fix;;
*)
(************************************************************************)
(* Co-fixpoints. *)
exception CoFixGuardError of env * guard_error
let anomaly_ill_typed () =
anomaly "check_one_cofix: too many arguments applied to constructor"
let rec codomain_is_coind env c =
let b = whd_betadeltaiota env c in
match kind_of_term b with
| Prod (x,a,b) ->
codomain_is_coind (push_rel (x, None, a) env) b
| _ ->
(try find_coinductive env b
with Not_found ->
raise (CoFixGuardError (env, CodomainNotInductiveType b)))
let check_one_cofix env nbfix def deftype =
let rec check_rec_call env alreadygrd n vlra t =
if not (noccur_with_meta n nbfix t) then
let c,args = decompose_app (whd_betadeltaiota env t) in
match kind_of_term c with
| Rel p when n <= p && p < n+nbfix ->
(* recursive call: must be guarded and no nested recursive
call allowed *)
if not alreadygrd then
raise (CoFixGuardError (env,UnguardedRecursiveCall t))
else if not(List.for_all (noccur_with_meta n nbfix) args) then
raise (CoFixGuardError (env,NestedRecursiveOccurrences))
| Construct (_,i as cstr_kn) ->
let lra = vlra.(i-1) in
let mI = inductive_of_constructor cstr_kn in
let (mib,mip) = lookup_mind_specif env mI in
let realargs = list_skipn mib.mind_nparams args in
let rec process_args_of_constr = function
| (t::lr), (rar::lrar) ->
if rar = mk_norec then
if noccur_with_meta n nbfix t
then process_args_of_constr (lr, lrar)
else raise (CoFixGuardError
(env,RecCallInNonRecArgOfConstructor t))
else
let spec = dest_subterms rar in
check_rec_call env true n spec t;
process_args_of_constr (lr, lrar)
| [],_ -> ()
| _ -> anomaly_ill_typed ()
in process_args_of_constr (realargs, lra)
| Lambda (x,a,b) ->
assert (args = []);
if noccur_with_meta n nbfix a then
let env' = push_rel (x, None, a) env in
check_rec_call env' alreadygrd (n+1) vlra b
else
raise (CoFixGuardError (env,RecCallInTypeOfAbstraction a))
| CoFix (j,(_,varit,vdefs as recdef)) ->
if (List.for_all (noccur_with_meta n nbfix) args)
then
let nbfix = Array.length vdefs in
if (array_for_all (noccur_with_meta n nbfix) varit) then
let env' = push_rec_types recdef env in
(Array.iter (check_rec_call env' alreadygrd (n+1) vlra) vdefs;
List.iter (check_rec_call env alreadygrd n vlra) args)
else
raise (CoFixGuardError (env,RecCallInTypeOfDef c))
else
raise (CoFixGuardError (env,UnguardedRecursiveCall c))
| Case (_,p,tm,vrest) ->
if (noccur_with_meta n nbfix p) then
if (noccur_with_meta n nbfix tm) then
if (List.for_all (noccur_with_meta n nbfix) args) then
Array.iter (check_rec_call env alreadygrd n vlra) vrest
else
raise (CoFixGuardError (env,RecCallInCaseFun c))
else
raise (CoFixGuardError (env,RecCallInCaseArg c))
else
raise (CoFixGuardError (env,RecCallInCasePred c))
| Meta _ -> ()
| Evar _ ->
List.iter (check_rec_call env alreadygrd n vlra) args
| _ -> raise (CoFixGuardError (env,NotGuardedForm t)) in
let (mind, _) = codomain_is_coind env deftype in
let vlra = lookup_subterms env mind in
check_rec_call env false 1 (dest_subterms vlra) def
(* The function which checks that the whole block of definitions
satisfies the guarded condition *)
let check_cofix env (bodynum,(names,types,bodies as recdef)) =
let nbfix = Array.length bodies in
for i = 0 to nbfix-1 do
let fixenv = push_rec_types recdef env in
try check_one_cofix fixenv nbfix bodies.(i) types.(i)
with CoFixGuardError (errenv,err) ->
error_ill_formed_rec_body errenv err names i
fixenv (judgment_of_fixpoint recdef)
done