(* $Id$ *) open Util open Pp open Names open Univ open Term open Sign open Environ open Evd open Instantiate open Reduction open Indrec open Pretype_errors let rec filter_unique = function | [] -> [] | x::l -> if List.mem x l then filter_unique (List.filter (fun y -> x<>y) l) else x::filter_unique l (* let distinct_id_list = let rec drec fresh = function [] -> List.rev fresh | id::rest -> let id' = next_ident_away_from id fresh in drec (id'::fresh) rest in drec [] *) (* let filter_sign p sign x = sign_it (fun id ty (v,ids,sgn) -> let (disc,v') = p v (id,ty) in if disc then (v', id::ids, sgn) else (v', ids, add_sign (id,ty) sgn)) sign (x,[],nil_sign) *) let evar_env evd = Global.env_of_context evd.evar_hyps (*------------------------------------* * functional operations on evar sets * *------------------------------------*) (* All ids of sign must be distincts! *) let new_isevar_sign env sigma typ instance = let sign = named_context env in if not (list_distinct (ids_of_named_context sign)) then error "new_isevar_sign: two vars have the same name"; let newev = Evd.new_evar() in let info = { evar_concl = typ; evar_hyps = sign; evar_body = Evar_empty; evar_info = None } in (Evd.add sigma newev info, mkEvar (newev,Array.of_list instance)) (* We don't try to guess in which sort the type should be defined, since any type has type Type. May cause some trouble, but not so far... *) let dummy_sort = mkType dummy_univ let make_evar_instance env = fold_named_context (fun env (id, b, _) l -> if b=None then mkVar id :: l else l) env [] (* Declaring any type to be in the sort Type shouldn't be harmful since cumulativity now includes Prop and Set in Type. *) let new_type_var env sigma = let instance = make_evar_instance env in let (sigma',c) = new_isevar_sign env sigma dummy_sort instance in (sigma', c) let split_evar_to_arrow sigma c = let (ev,args) = destEvar c in let evd = Evd.map sigma ev in let evenv = evar_env evd in let (sigma1,dom) = new_type_var evenv sigma in let hyps = evd.evar_hyps in let nvar = next_ident_away (id_of_string "x") (ids_of_named_context hyps) in let newenv = push_named_assum (nvar, dom) evenv in let (sigma2,rng) = new_type_var newenv sigma1 in let prod = mkProd (named_hd newenv dom Anonymous, dom, subst_var nvar rng) in let sigma3 = Evd.define sigma2 ev prod in let dsp = num_of_evar dom in let rsp = num_of_evar rng in (sigma3, mkEvar (dsp,args), mkEvar (rsp, array_cons (mkRel 1) (Array.map (lift 1) args))) (* Redefines an evar with a smaller context (i.e. it may depend on less * variables) such that c becomes closed. * Example: in [x:?1; y:(list ?2)] x=y /\ x=(nil bool) * ?3 <-- ?1 no pb: env of ?3 is larger than ?1's * ?1 <-- (list ?2) pb: ?2 may depend on x, but not ?1. * What we do is that ?2 is defined by a new evar ?4 whose context will be * a prefix of ?2's env, included in ?1's env. *) let do_restrict_hyps sigma ev args = let args = Array.to_list args in let evd = Evd.map sigma ev in let env = evar_env evd in let hyps = evd.evar_hyps in let (_,(rsign,ncargs)) = List.fold_left (fun (sign,(rs,na)) a -> (List.tl sign, if not(closed0 a) then (rs,na) else (add_named_decl (List.hd sign) rs, a::na))) (hyps,([],[])) args in let sign' = List.rev rsign in let env' = change_hyps (fun _ -> sign') env in let instance = make_evar_instance env' in let (sigma',nc) = new_isevar_sign env' sigma evd.evar_concl instance in let sigma'' = Evd.define sigma' ev nc in (sigma'', nc) (*------------------------------------* * operations on the evar constraints * *------------------------------------*) type evar_constraint = conv_pb * constr * constr type 'a evar_defs = 'a Evd.evar_map ref (* ise_try [f1;...;fn] tries fi() for i=1..n, restoring the evar constraints * when fi returns false or an exception. Returns true if one of the fi * returns true, and false if every fi return false (in the latter case, * the evar constraints are restored). *) let ise_try isevars l = let u = !isevars in let rec test = function [] -> isevars := u; false | f::l -> (try f() with reraise -> isevars := u; raise reraise) or (isevars := u; test l) in test l (* say if the section path sp corresponds to an existential *) let ise_in_dom isevars sp = Evd.in_dom !isevars sp (* map the given section path to the enamed_declaration *) let ise_map isevars sp = Evd.map !isevars sp (* define the existential of section path sp as the constr body *) let ise_define isevars sp body = isevars := Evd.define !isevars sp body (* Does k corresponds to an (un)defined existential ? *) let ise_undefined isevars c = match kind_of_term c with | IsEvar (n,_) -> not (Evd.is_defined !isevars n) | _ -> false let ise_defined isevars c = match kind_of_term c with | IsEvar (n,_) -> Evd.is_defined !isevars n | _ -> false let need_restriction isevars args = not (array_for_all closed0 args) (* We try to instanciate the evar assuming the body won't depend * on arguments that are not Rels or Vars, or appearing several times. *) (* Note: error_not_clean should not be an error: it simply means that the * conversion test that lead to the faulty call to [real_clean] should return * false. The problem is that we won't get the right error message. *) let real_clean isevars sp args rhs = let subst = List.map (fun (x,y) -> (y,mkVar x)) (filter_unique args) in let rec subs k t = match kind_of_term t with | IsRel i -> if i<=k then t else (try List.assoc (mkRel (i-k)) subst with Not_found -> t) | IsEvar (ev,args) -> let args' = Array.map (subs k) args in if need_restriction isevars args' then if Evd.is_defined !isevars ev then subs k (existential_value !isevars (ev,args')) else begin let (sigma,rc) = do_restrict_hyps !isevars ev args' in isevars := sigma; rc end else mkEvar (ev,args') | IsVar _ -> (try List.assoc t subst with Not_found -> t) | _ -> map_constr_with_binders succ subs k t in let body = subs 0 rhs in if not (closed0 body) then error_not_clean CCI empty_env sp body; body let make_evar_instance_with_rel env = let n = rel_context_length (rel_context env) in let vars = fold_named_context (fun env (id,b,_) l -> if b=None then mkVar id :: l else l) env [] in snd (fold_rel_context (fun env (_,b,_) (i,l) -> (i-1, if b=None then mkRel i :: l else l)) env (n,vars)) let make_subst env args = snd (fold_named_context (fun env (id,b,c) (args,l as g) -> match b, args with | None, a::rest -> (rest, (id,a)::l) | Some _, _ -> g | _ -> anomaly "Instance does not match its signature") env (List.rev args,[])) (* [new_isevar] declares a new existential in an env env with type typ *) (* Converting the env into the sign of the evar to define *) let new_isevar isevars env typ k = let subst,env' = push_rel_context_to_named_context env in let typ' = substl subst typ in let instance = make_evar_instance_with_rel env in let (sigma',evar) = new_isevar_sign env' !isevars typ' instance in isevars := sigma'; evar (* [evar_define] solves the problem lhs = rhs when lhs is an uninstantiated * evar, i.e. tries to find the body ?sp for lhs=mkEvar (sp,args) * ?sp [ sp.hyps \ args ] unifies to rhs * ?sp must be a closed term, not referring to itself. * Not so trivial because some terms of args may be terms that are not * variables. In this case, the non-var-or-Rels arguments are replaced * by . [clean_rhs] will ignore this part of the subtitution. * This leads to incompleteness (we don't deal with pbs that require * inference of dependent types), but it seems sensible. * * If after cleaning, some free vars still occur, the function [restrict_hyps] * tries to narrow the env of the evars that depend on Rels. * * If after that free Rels still occur it means that the instantiation * cannot be done, as in [x:?1; y:nat; z:(le y y)] x=z * ?1 would be instantiated by (le y y) but y is not in the scope of ?1 *) let keep_rels_and_vars c = match kind_of_term c with | IsVar _ | IsRel _ -> c | _ -> mkImplicit (* Mettre mkMeta ?? *) let evar_define isevars (ev,argsv) rhs = if occur_evar ev rhs then error_occur_check CCI empty_env ev rhs; let args = List.map keep_rels_and_vars (Array.to_list argsv) in let evd = ise_map isevars ev in (* the substitution to invert *) let worklist = make_subst (evar_env evd) args in let body = real_clean isevars ev worklist rhs in ise_define isevars ev body; [ev] (*-------------------*) (* Auxiliary functions for the conversion algorithms modulo evars *) let has_undefined_isevars isevars t = try let _ = whd_ise !isevars t in false with Uninstantiated_evar _ -> true let head_is_evar isevars = let rec hrec k = match kind_of_term k with | IsEvar (n,_) -> not (Evd.is_defined !isevars n) | IsApp (f,_) -> hrec f | IsCast (c,_) -> hrec c | _ -> false in hrec let rec is_eliminator c = match kind_of_term c with | IsApp _ -> true | IsMutCase _ -> true | IsCast (c,_) -> is_eliminator c | _ -> false let head_is_embedded_evar isevars c = (head_is_evar isevars c) & (is_eliminator c) let head_evar = let rec hrec c = match kind_of_term c with | IsEvar (ev,_) -> ev | IsMutCase (_,_,c,_) -> hrec c | IsApp (c,_) -> hrec c | IsCast (c,_) -> hrec c | _ -> failwith "headconstant" in hrec (* This code (i.e. solve_pb, etc.) takes a unification * problem, and tries to solve it. If it solves it, then it removes * all the conversion problems, and re-runs conversion on each one, in * the hopes that the new solution will aid in solving them. * * The kinds of problems it knows how to solve are those in which * the usable arguments of an existential var are all themselves * universal variables. * The solution to this problem is to do renaming for the Var's, * to make them match up with the Var's which are found in the * hyps of the existential, to do a "pop" for each Rel which is * not an argument of the existential, and a subst1 for each which * is, again, with the corresponding variable. This is done by * Tradevar.evar_define * * Thus, we take the arguments of the existential which we are about * to assign, and zip them with the identifiers in the hypotheses. * Then, we process all the Var's in the arguments, and sort the * Rel's into ascending order. Then, we just march up, doing * subst1's and pop's. * * NOTE: We can do this more efficiently for the relative arguments, * by building a long substituend by hand, but this is a pain in the * ass. *) let conversion_problems = ref ([] : evar_constraint list) let reset_problems () = conversion_problems := [] let add_conv_pb pb = (conversion_problems := pb::!conversion_problems) let status_changed lev (pbty,t1,t2) = try List.mem (head_evar t1) lev or List.mem (head_evar t2) lev with Failure _ -> try List.mem (head_evar t2) lev with Failure _ -> false let get_changed_pb lev = let (pbs,pbs1) = List.fold_left (fun (pbs,pbs1) pb -> if status_changed lev pb then (pb::pbs,pbs1) else (pbs,pb::pbs1)) ([],[]) !conversion_problems in conversion_problems := pbs1; pbs (* Solve pbs (?i x1..xn) = (?i y1..yn) which arises often in fixpoint * definitions. We try to unify the xi with the yi pairwise. The pairs * that don't unify are discarded (i.e. ?i is redefined so that it does not * depend on these args). *) let solve_refl conv_algo env isevars ev argsv1 argsv2 = if argsv1 = argsv2 then [] else let evd = Evd.map !isevars ev in let env = evar_env evd in let hyps = evd.evar_hyps in let (_,rsign) = array_fold_left2 (fun (sgn,rsgn) a1 a2 -> if conv_algo env isevars CONV a1 a2 then (List.tl sgn, add_named_decl (List.hd sgn) rsgn) else (List.tl sgn, rsgn)) (hyps,[]) argsv1 argsv2 in let nsign = List.rev rsign in let nargs = (Array.of_list (List.map mkVar (ids_of_named_context nsign))) in let newev = Evd.new_evar () in let info = { evar_concl = evd.evar_concl; evar_hyps = nsign; evar_body = Evar_empty; evar_info = None } in isevars := Evd.define (Evd.add !isevars newev info) ev (mkEvar (newev,nargs)); [ev] (* Tries to solve problem t1 = t2. * Precondition: t1 is an uninstanciated evar * Returns an optional list of evars that were instantiated, or None * if the problem couldn't be solved. *) (* Rq: uncomplete algorithm if pbty = CONV_X_LEQ ! *) let solve_simple_eqn conv_algo env isevars (pbty,(n1,args1 as ev1),t2) = let t2 = nf_ise1 !isevars t2 in let lsp = match kind_of_term t2 with | IsEvar (n2,args2 as ev2) when not (Evd.is_defined !isevars n2) -> if n1 = n2 then solve_refl conv_algo env isevars n1 args1 args2 else if Array.length args1 < Array.length args2 then evar_define isevars ev2 (mkEvar ev1) else evar_define isevars ev1 t2 | _ -> evar_define isevars ev1 t2 in let pbs = get_changed_pb lsp in List.for_all (fun (pbty,t1,t2) -> conv_algo env isevars pbty t1 t2) pbs (* Operations on value/type constraints *) type type_constraint = constr option type val_constraint = constr option (* Old comment... * Basically, we have the following kind of constraints (in increasing * strength order): * (false,(None,None)) -> no constraint at all * (true,(None,None)) -> we must build a judgement which _TYPE is a kind * (_,(None,Some ty)) -> we must build a judgement which _TYPE is ty * (_,(Some v,_)) -> we must build a judgement which _VAL is v * Maybe a concrete datatype would be easier to understand. * We differentiate (true,(None,None)) from (_,(None,Some Type)) * because otherwise Case(s) would be misled, as in * (n:nat) Case n of bool [_]nat end would infer the predicate Type instead * of Set. *) (* The empty type constraint *) let empty_tycon = None (* Builds a type constraint *) let mk_tycon ty = Some ty (* Constrains the value of a type *) let empty_valcon = None (* Builds a value constraint *) let mk_valcon c = Some c (* Propagation of constraints through application and abstraction: Given a type constraint on a functional term, returns the type constraint on its domain and codomain. If the input constraint is an evar instantiate it with the product of 2 new evars. *) let split_tycon loc env isevars = function | None -> None,None | Some c -> let t = whd_betadeltaiota env !isevars c in match kind_of_term t with | IsProd (na,dom,rng) -> Some dom, Some rng | _ -> if ise_undefined isevars t then let (sigma,dom,rng) = split_evar_to_arrow !isevars t in isevars := sigma; Some dom, Some rng else Stdpp.raise_with_loc loc (Type_errors.TypeError (CCI,env,Type_errors.NotProduct c)) let valcon_of_tycon x = x