(************************************************************************) (* v * The Coq Proof Assistant / The Coq Development Team *) (* idset | c::cl -> if Idset.mem c idset then raise (InductiveError (SameNamesConstructors c)) else check (Idset.add c idset) cl in check (* [mind_check_names mie] checks the names of an inductive types declaration, and raises the corresponding exceptions when two types or two constructors have the same name. *) let mind_check_names mie = let rec check indset cstset = function | [] -> () | ind::inds -> let id = ind.mind_entry_typename in let cl = ind.mind_entry_consnames in if Idset.mem id indset then raise (InductiveError (SameNamesTypes id)) else let cstset' = check_constructors_names cstset cl in check (Idset.add id indset) cstset' inds in check Idset.empty Idset.empty mie.mind_entry_inds (* The above verification is not necessary from the kernel point of vue since inductive and constructors are not referred to by their name, but only by the name of the inductive packet and an index. *) let mind_check_arities env mie = let check_arity id c = if not (is_arity env c) then raise (InductiveError (NotAnArity id)) in List.iter (fun {mind_entry_typename=id; mind_entry_arity=ar} -> check_arity id ar) mie.mind_entry_inds (************************************************************************) (************************************************************************) (* Typing the arities and constructor types *) let is_logic_type t = (t.utj_type = prop_sort) (* [infos] is a sequence of pair [islogic,issmall] for each type in the product of a constructor or arity *) let is_small infos = List.for_all (fun (logic,small) -> small) infos let is_logic_constr infos = List.for_all (fun (logic,small) -> logic) infos (* An inductive definition is a "unit" if it has only one constructor and that all arguments expected by this constructor are logical, this is the case for equality, conjunction of logical properties *) let is_unit constrsinfos = match constrsinfos with (* One info = One constructor *) | [constrinfos] -> is_logic_constr constrinfos | [] -> (* type without constructors *) true | _ -> false let rec infos_and_sort env t = let t = whd_betadeltaiota env t in match kind_of_term t with | Prod (name,c1,c2) -> let (varj,_) = infer_type env c1 in let env1 = Environ.push_rel (name,None,varj.utj_val) env in let logic = is_logic_type varj in let small = Term.is_small varj.utj_type in (logic,small) :: (infos_and_sort env1 c2) | _ when is_constructor_head t -> [] | _ -> (* don't fail if not positive, it is tested later *) [] let small_unit constrsinfos = let issmall = List.for_all is_small constrsinfos and isunit = is_unit constrsinfos in issmall, isunit (* Computing the levels of polymorphic inductive types For each inductive type of a block that is of level u_i, we have the constraints that u_i >= v_i where v_i is the type level of the types of the constructors of this inductive type. Each v_i depends of some of the u_i and of an extra (maybe non variable) universe, say w_i that summarize all the other constraints. Typically, for three inductive types, we could have u1,u2,u3,w1 <= u1 u1 w2 <= u2 u2,u3,w3 <= u3 From this system of inequations, we shall deduce w1,w2,w3 <= u1 w1,w2 <= u2 w1,w2,w3 <= u3 *) let extract_level (_,_,_,lc,lev) = (* Enforce that the level is not in Prop if more than two constructors *) if Array.length lc >= 2 then sup type0_univ lev else lev let inductive_levels arities inds = let levels = Array.map pi3 arities in let cstrs_levels = Array.map extract_level inds in (* Take the transitive closure of the system of constructors *) (* level constraints and remove the recursive dependencies *) solve_constraints_system levels cstrs_levels (* This (re)computes informations relevant to extraction and the sort of an arity or type constructor; we do not to recompute universes constraints *) let constraint_list_union = List.fold_left Constraint.union Constraint.empty let infer_constructor_packet env_ar_par params lc = (* type-check the constructors *) let jlc,cstl = List.split (List.map (infer_type env_ar_par) lc) in let cst = constraint_list_union cstl in let jlc = Array.of_list jlc in (* generalize the constructor over the parameters *) let lc'' = Array.map (fun j -> it_mkProd_or_LetIn j.utj_val params) jlc in (* compute the max of the sorts of the products of the constructor type *) let level = max_inductive_sort (Array.map (fun j -> j.utj_type) jlc) in (* compute *) let info = small_unit (List.map (infos_and_sort env_ar_par) lc) in (info,lc'',level,cst) (* Type-check an inductive definition. Does not check positivity conditions. *) let typecheck_inductive env mie = if mie.mind_entry_inds = [] then anomaly "empty inductive types declaration"; (* Check unicity of names *) mind_check_names mie; (* Params are typed-checked here *) let env_params, params, cst1 = infer_local_decls env mie.mind_entry_params in (* We first type arity of each inductive definition *) (* This allows to build the environment of arities and to share *) (* the set of constraints *) let cst, env_arities, rev_arity_list = List.fold_left (fun (cst,env_ar,l) ind -> (* Arities (without params) are typed-checked here *) let arity, cst2 = infer_type env_params ind.mind_entry_arity in (* We do not need to generate the universe of full_arity; if later, after the validation of the inductive definition, full_arity is used as argument or subject to cast, an upper universe will be generated *) let full_arity = it_mkProd_or_LetIn arity.utj_val params in let cst = Constraint.union cst cst2 in let id = ind.mind_entry_typename in let env_ar' = push_rel (Name id, None, full_arity) (add_constraints cst2 env_ar) in let lev = (* Decide that if the conclusion is not explicitly Type *) (* then the inductive type is not polymorphic *) match kind_of_term (snd (decompose_prod_assum arity.utj_val)) with | Sort (Type u) -> Some u | _ -> None in (cst,env_ar',(id,full_arity,lev)::l)) (cst1,env,[]) mie.mind_entry_inds in let arity_list = List.rev rev_arity_list in (* builds the typing context "Gamma, I1:A1, ... In:An, params" *) let env_ar_par = push_rel_context params (add_constraints cst1 env_arities) in (* Now, we type the constructors (without params) *) let inds,cst = List.fold_right2 (fun ind arity_data (inds,cst) -> let (info,lc',cstrs_univ,cst') = infer_constructor_packet env_ar_par params ind.mind_entry_lc in let consnames = ind.mind_entry_consnames in let ind' = (arity_data,consnames,info,lc',cstrs_univ) in (ind'::inds, Constraint.union cst cst')) mie.mind_entry_inds arity_list ([],cst) in let inds = Array.of_list inds in let arities = Array.of_list arity_list in let param_ccls = List.fold_left (fun l (_,b,p) -> if b = None then let _,c = dest_prod_assum env p in let u = match kind_of_term c with Sort (Type u) -> Some u | _ -> None in u::l else l) [] params in (* Compute/check the sorts of the inductive types *) let ind_min_levels = inductive_levels arities inds in let inds, cst = array_fold_map2' (fun ((id,full_arity,ar_level),cn,info,lc,_) lev cst -> let sign, s = dest_arity env full_arity in let status,cst = match s with | Type u when ar_level <> None (* Explicitly polymorphic *) && no_upper_constraints u cst -> (* The polymorphic level is a function of the level of the *) (* conclusions of the parameters *) (* We enforce [u >= lev] in case [lev] has a strict upper *) (* constraints over [u] *) Inr (param_ccls, lev), enforce_geq u lev cst | Type u (* Not an explicit occurrence of Type *) -> Inl (info,full_arity,s), enforce_geq u lev cst | Prop Pos when engagement env <> Some ImpredicativeSet -> (* Predicative set: check that the content is indeed predicative *) if not (is_type0m_univ lev) & not (is_type0_univ lev) then error "Large non-propositional inductive types must be in Type."; Inl (info,full_arity,s), cst | Prop _ -> Inl (info,full_arity,s), cst in (id,cn,lc,(sign,status)),cst) inds ind_min_levels cst in (env_arities, params, inds, cst) (************************************************************************) (************************************************************************) (* Positivity *) type ill_formed_ind = | LocalNonPos of int | LocalNotEnoughArgs of int | LocalNotConstructor | LocalNonPar of int * int exception IllFormedInd of ill_formed_ind (* [mind_extract_params mie] extracts the params from an inductive types declaration, and checks that they are all present (and all the same) for all the given types. *) let mind_extract_params = decompose_prod_n_assum let explain_ind_err id ntyp env0 nbpar c nargs err = let (lpar,c') = mind_extract_params nbpar c in let env = push_rel_context lpar env0 in match err with | LocalNonPos kt -> raise (InductiveError (NonPos (env,c',mkRel (kt+nbpar)))) | LocalNotEnoughArgs kt -> raise (InductiveError (NotEnoughArgs (env,c',mkRel (kt+nbpar)))) | LocalNotConstructor -> raise (InductiveError (NotConstructor (env,id,c',mkRel (ntyp+nbpar),nbpar,nargs))) | LocalNonPar (n,l) -> raise (InductiveError (NonPar (env,c',n,mkRel (nbpar-n+1), mkRel (l+nbpar)))) let failwith_non_pos n ntypes c = for k = n to n + ntypes - 1 do if not (noccurn k c) then raise (IllFormedInd (LocalNonPos (k-n+1))) done let failwith_non_pos_vect n ntypes v = Array.iter (failwith_non_pos n ntypes) v; anomaly "failwith_non_pos_vect: some k in [n;n+ntypes-1] should occur" let failwith_non_pos_list n ntypes l = List.iter (failwith_non_pos n ntypes) l; anomaly "failwith_non_pos_list: some k in [n;n+ntypes-1] should occur" (* Check the inductive type is called with the expected parameters *) let check_correct_par (env,n,ntypes,_) hyps l largs = let nparams = rel_context_nhyps hyps in let largs = Array.of_list largs in if Array.length largs < nparams then raise (IllFormedInd (LocalNotEnoughArgs l)); let (lpar,largs') = array_chop nparams largs in let nhyps = List.length hyps in let rec check k index = function | [] -> () | (_,Some _,_)::hyps -> check k (index+1) hyps | _::hyps -> match kind_of_term (whd_betadeltaiota env lpar.(k)) with | Rel w when w = index -> check (k-1) (index+1) hyps | _ -> raise (IllFormedInd (LocalNonPar (k+1,l))) in check (nparams-1) (n-nhyps) hyps; if not (array_for_all (noccur_between n ntypes) largs') then failwith_non_pos_vect n ntypes largs' (* Computes the maximum number of recursive parameters : the first parameters which are constant in recursive arguments n is the current depth, nmr is the maximum number of possible recursive parameters *) let compute_rec_par (env,n,_,_) hyps nmr largs = if nmr = 0 then 0 else (* start from 0, hyps will be in reverse order *) let (lpar,_) = list_chop nmr largs in let rec find k index = function ([],_) -> nmr | (_,[]) -> assert false (* |hyps|>=nmr *) | (lp,(_,Some _,_)::hyps) -> find k (index-1) (lp,hyps) | (p::lp,_::hyps) -> ( match kind_of_term (whd_betadeltaiota env p) with | Rel w when w = index -> find (k+1) (index-1) (lp,hyps) | _ -> k) in find 0 (n-1) (lpar,List.rev hyps) (* This removes global parameters of the inductive types in lc (for nested inductive types only ) *) let abstract_mind_lc env ntyps npars lc = if npars = 0 then lc else let make_abs = list_tabulate (function i -> lambda_implicit_lift npars (mkRel (i+1))) ntyps in Array.map (substl make_abs) lc (* [env] is the typing environment [n] is the dB of the last inductive type [ntypes] is the number of inductive types in the definition (i.e. range of inductives is [n; n+ntypes-1]) [lra] is the list of recursive tree of each variable *) let ienv_push_var (env, n, ntypes, lra) (x,a,ra) = (push_rel (x,None,a) env, n+1, ntypes, (Norec,ra)::lra) let ienv_push_inductive (env, n, ntypes, ra_env) (mi,lpar) = let auxntyp = 1 in let specif = lookup_mind_specif env mi in let env' = push_rel (Anonymous,None, hnf_prod_applist env (type_of_inductive env specif) lpar) env in let ra_env' = (Imbr mi,(Rtree.mk_rec_calls 1).(0)) :: List.map (fun (r,t) -> (r,Rtree.lift 1 t)) ra_env in (* New index of the inductive types *) let newidx = n + auxntyp in (env', newidx, ntypes, ra_env') let array_min nmr a = if nmr = 0 then 0 else Array.fold_left (fun k (nmri,_) -> min k nmri) nmr a (* The recursive function that checks positivity and builds the list of recursive arguments *) let check_positivity_one (env, _,ntypes,_ as ienv) hyps i nargs lcnames indlc = let lparams = rel_context_length hyps in let nmr = rel_context_nhyps hyps in (* Checking the (strict) positivity of a constructor argument type [c] *) let rec check_pos (env, n, ntypes, ra_env as ienv) nmr c = let x,largs = decompose_app (whd_betadeltaiota env c) in match kind_of_term x with | Prod (na,b,d) -> assert (largs = []); (match weaker_noccur_between env n ntypes b with None -> failwith_non_pos_list n ntypes [b] | Some b -> check_pos (ienv_push_var ienv (na, b, mk_norec)) nmr d) | Rel k -> (try let (ra,rarg) = List.nth ra_env (k-1) in let nmr1 = (match ra with Mrec _ -> compute_rec_par ienv hyps nmr largs | _ -> nmr) in if not (List.for_all (noccur_between n ntypes) largs) then failwith_non_pos_list n ntypes largs else (nmr1,rarg) with Failure _ | Invalid_argument _ -> (nmr,mk_norec)) | Ind ind_kn -> (* If the inductive type being defined appears in a parameter, then we have a nested indtype *) if List.for_all (noccur_between n ntypes) largs then (nmr,mk_norec) else check_positive_nested ienv nmr (ind_kn, largs) | err -> if noccur_between n ntypes x && List.for_all (noccur_between n ntypes) largs then (nmr,mk_norec) else failwith_non_pos_list n ntypes (x::largs) (* accesses to the environment are not factorised, but is it worth? *) and check_positive_nested (env,n,ntypes,ra_env as ienv) nmr (mi, largs) = let (mib,mip) = lookup_mind_specif env mi in let auxnpar = mib.mind_nparams_rec in let (lpar,auxlargs) = try list_chop auxnpar largs with Failure _ -> raise (IllFormedInd (LocalNonPos n)) in (* If the inductive appears in the args (non params) then the definition is not positive. *) if not (List.for_all (noccur_between n ntypes) auxlargs) then raise (IllFormedInd (LocalNonPos n)); (* We do not deal with imbricated mutual inductive types *) let auxntyp = mib.mind_ntypes in if auxntyp <> 1 then raise (IllFormedInd (LocalNonPos n)); (* The nested inductive type with parameters removed *) let auxlcvect = abstract_mind_lc env auxntyp auxnpar mip.mind_nf_lc in (* Extends the environment with a variable corresponding to the inductive def *) let (env',_,_,_ as ienv') = ienv_push_inductive ienv (mi,lpar) in (* Parameters expressed in env' *) let lpar' = List.map (lift auxntyp) lpar in let irecargs_nmr = (* fails if the inductive type occurs non positively *) (* when substituted *) Array.map (function c -> let c' = hnf_prod_applist env' c lpar' in check_constructors ienv' false nmr c') auxlcvect in let irecargs = Array.map snd irecargs_nmr and nmr' = array_min nmr irecargs_nmr in (nmr',(Rtree.mk_rec [|mk_paths (Imbr mi) irecargs|]).(0)) (* check the inductive types occur positively in the products of C, if check_head=true, also check the head corresponds to a constructor of the ith type *) and check_constructors ienv check_head nmr c = let rec check_constr_rec (env,n,ntypes,ra_env as ienv) nmr lrec c = let x,largs = decompose_app (whd_betadeltaiota env c) in match kind_of_term x with | Prod (na,b,d) -> assert (largs = []); let nmr',recarg = check_pos ienv nmr b in let ienv' = ienv_push_var ienv (na,b,mk_norec) in check_constr_rec ienv' nmr' (recarg::lrec) d | hd -> if check_head then if hd = Rel (n+ntypes-i-1) then check_correct_par ienv hyps (ntypes-i) largs else raise (IllFormedInd LocalNotConstructor) else if not (List.for_all (noccur_between n ntypes) largs) then raise (IllFormedInd (LocalNonPos n)); (nmr,List.rev lrec) in check_constr_rec ienv nmr [] c in let irecargs_nmr = array_map2 (fun id c -> let _,rawc = mind_extract_params lparams c in try check_constructors ienv true nmr rawc with IllFormedInd err -> explain_ind_err id (ntypes-i) env lparams c nargs err) (Array.of_list lcnames) indlc in let irecargs = Array.map snd irecargs_nmr and nmr' = array_min nmr irecargs_nmr in (nmr', mk_paths (Mrec i) irecargs) let check_positivity env_ar params inds = let ntypes = Array.length inds in let rc = Array.mapi (fun j t -> (Mrec j,t)) (Rtree.mk_rec_calls ntypes) in let lra_ind = List.rev (Array.to_list rc) in let lparams = rel_context_length params in let nmr = rel_context_nhyps params in let check_one i (_,lcnames,lc,(sign,_)) = let ra_env = list_tabulate (fun _ -> (Norec,mk_norec)) lparams @ lra_ind in let ienv = (env_ar, 1+lparams, ntypes, ra_env) in let nargs = rel_context_nhyps sign - nmr in check_positivity_one ienv params i nargs lcnames lc in let irecargs_nmr = Array.mapi check_one inds in let irecargs = Array.map snd irecargs_nmr and nmr' = array_min nmr irecargs_nmr in (nmr',Rtree.mk_rec irecargs) (************************************************************************) (************************************************************************) (* Build the inductive packet *) (* Elimination sorts *) let is_recursive = Rtree.is_infinite (* let rec one_is_rec rvec = List.exists (function Mrec(i) -> List.mem i listind | Imbr(_,lvec) -> array_exists one_is_rec lvec | Norec -> false) rvec in array_exists one_is_rec *) (* Allowed eliminations *) let all_sorts = [InProp;InSet;InType] let small_sorts = [InProp;InSet] let logical_sorts = [InProp] let allowed_sorts issmall isunit s = match family_of_sort s with (* Type: all elimination allowed *) | InType -> all_sorts (* Small Set is predicative: all elimination allowed *) | InSet when issmall -> all_sorts (* Large Set is necessarily impredicative: forbids large elimination *) | InSet -> small_sorts (* Unitary/empty Prop: elimination to all sorts are realizable *) (* unless the type is large. If it is large, forbids large elimination *) (* which otherwise allows to simulate the inconsistent system Type:Type *) | InProp when isunit -> if issmall then all_sorts else small_sorts (* Other propositions: elimination only to Prop *) | InProp -> logical_sorts let fold_inductive_blocks f = Array.fold_left (fun acc (_,_,lc,(arsign,_)) -> f (Array.fold_left f acc lc) (it_mkProd_or_LetIn (* dummy *) mkSet arsign)) let used_section_variables env inds = let ids = fold_inductive_blocks (fun l c -> Idset.union (Environ.global_vars_set env c) l) Idset.empty inds in keep_hyps env ids let build_inductive env env_ar params isrecord isfinite inds nmr recargs cst = let ntypes = Array.length inds in (* Compute the set of used section variables *) let hyps = used_section_variables env inds in let nparamargs = rel_context_nhyps params in (* Check one inductive *) let build_one_packet (id,cnames,lc,(ar_sign,ar_kind)) recarg = (* Type of constructors in normal form *) let splayed_lc = Array.map (dest_prod_assum env_ar) lc in let nf_lc = Array.map (fun (d,b) -> it_mkProd_or_LetIn b d) splayed_lc in let nf_lc = if nf_lc = lc then lc else nf_lc in let consnrealargs = Array.map (fun (d,_) -> rel_context_length d - rel_context_length params) splayed_lc in (* Elimination sorts *) let arkind,kelim = match ar_kind with | Inr (param_levels,lev) -> Polymorphic { poly_param_levels = param_levels; poly_level = lev; }, all_sorts | Inl ((issmall,isunit),ar,s) -> let kelim = allowed_sorts issmall isunit s in Monomorphic { mind_user_arity = ar; mind_sort = s; }, kelim in (* Assigning VM tags to constructors *) let nconst, nblock = ref 0, ref 0 in let transf num = let arity = List.length (dest_subterms recarg).(num) in if arity = 0 then let p = (!nconst, 0) in incr nconst; p else let p = (!nblock + 1, arity) in incr nblock; p (* les tag des constructeur constant commence a 0, les tag des constructeur non constant a 1 (0 => accumulator) *) in let rtbl = Array.init (List.length cnames) transf in (* Build the inductive packet *) { mind_typename = id; mind_arity = arkind; mind_arity_ctxt = ar_sign; mind_nrealargs = rel_context_nhyps ar_sign - nparamargs; mind_kelim = kelim; mind_consnames = Array.of_list cnames; mind_consnrealdecls = consnrealargs; mind_user_lc = lc; mind_nf_lc = nf_lc; mind_recargs = recarg; mind_nb_constant = !nconst; mind_nb_args = !nblock; mind_reloc_tbl = rtbl; } in let packets = array_map2 build_one_packet inds recargs in (* Build the mutual inductive *) { mind_record = isrecord; mind_ntypes = ntypes; mind_finite = isfinite; mind_hyps = hyps; mind_nparams = nparamargs; mind_nparams_rec = nmr; mind_params_ctxt = params; mind_packets = packets; mind_constraints = cst; mind_equiv = None; } (************************************************************************) (************************************************************************) let check_inductive env mie = (* First type-check the inductive definition *) let (env_ar, params, inds, cst) = typecheck_inductive env mie in (* Then check positivity conditions *) let (nmr,recargs) = check_positivity env_ar params inds in (* Build the inductive packets *) build_inductive env env_ar params mie.mind_entry_record mie.mind_entry_finite inds nmr recargs cst