diff options
Diffstat (limited to 'pretyping/cases.ml')
| -rw-r--r-- | pretyping/cases.ml | 87 |
1 files changed, 36 insertions, 51 deletions
diff --git a/pretyping/cases.ml b/pretyping/cases.ml index 7e33cc1d4..98d300088 100644 --- a/pretyping/cases.ml +++ b/pretyping/cases.ml @@ -1870,22 +1870,16 @@ let inh_conv_coerce_to_tycon loc env evdref j tycon = (* We put the tycon inside the arity signature, possibly discovering dependencies. *) -let add_subst c len (rel_subst,var_subst) = - match kind_of_term c with - | Rel n -> (n,len) :: rel_subst, var_subst - | Var id -> rel_subst, (id,len) :: var_subst - | _ -> assert false - let prepare_predicate_from_arsign_tycon env sigma loc tomatchs arsign c = let nar = List.fold_left (fun n sign -> Context.Rel.nhyps sign + n) 0 arsign in - let (rel_subst,var_subst), len = + let subst, len = List.fold_right2 (fun (tm, tmtype) sign (subst, len) -> let signlen = List.length sign in match kind_of_term tm with - | Rel _ | Var _ when dependent tm c + | Rel n when dependent tm c && Int.equal signlen 1 (* The term to match is not of a dependent type itself *) -> - (add_subst tm len subst, len - signlen) - | Rel _ | Var _ when signlen > 1 (* The term is of a dependent type, + ((n, len) :: subst, len - signlen) + | Rel n when signlen > 1 (* The term is of a dependent type, maybe some variable in its type appears in the tycon. *) -> (match tmtype with NotInd _ -> (subst, len - signlen) @@ -1894,36 +1888,28 @@ let prepare_predicate_from_arsign_tycon env sigma loc tomatchs arsign c = List.fold_left (fun (subst, len) arg -> match kind_of_term arg with - | Rel _ | Var _ when dependent arg c -> - (add_subst arg len subst, pred len) + | Rel n when dependent arg c -> + ((n, len) :: subst, pred len) | _ -> (subst, pred len)) (subst, len) realargs in let subst = - if dependent tm c && List.for_all (fun c -> isRel c || isVar c) realargs - then add_subst tm len subst else subst + if dependent tm c && List.for_all isRel realargs + then (n, len) :: subst else subst in (subst, pred len)) | _ -> (subst, len - signlen)) - (List.rev tomatchs) arsign (([],[]), nar) + (List.rev tomatchs) arsign ([], nar) in let rec predicate lift c = match kind_of_term c with | Rel n when n > lift -> (try (* Make the predicate dependent on the matched variable *) - let idx = Int.List.assoc (n - lift) rel_subst in + let idx = Int.List.assoc (n - lift) subst in mkRel (idx + lift) with Not_found -> - (* A variable that is not matched, lift over the arsign *) + (* A variable that is not matched, lift over the arsign. *) mkRel (n + nar)) - | Var id -> - (try - (* Make the predicate dependent on the matched variable *) - let idx = Id.List.assoc id var_subst in - mkRel (idx + lift) - with Not_found -> - (* A variable that is not matched *) - c) | _ -> map_constr_with_binders succ predicate lift c in @@ -1944,39 +1930,38 @@ let prepare_predicate_from_arsign_tycon env sigma loc tomatchs arsign c = let prepare_predicate loc typing_fun env sigma tomatchs arsign tycon pred = let preds = - match pred with + match pred, tycon with (* No return clause *) - | None -> - let sigma,t = - match tycon with - | Some t -> sigma, t - | None -> - (* No type constraint: we first create a generic evar type constraint *) - let src = (loc, Evar_kinds.CasesType false) in - let sigma = Sigma.Unsafe.of_evar_map sigma in - let Sigma ((t, _), sigma, _) = new_type_evar env sigma univ_flexible_alg ~src in - let sigma = Sigma.to_evar_map sigma in - sigma, t in - (* First strategy: we build an "inversion" predicate, also replacing the *) - (* dependencies with existential variables *) + | None, Some t when not (noccur_with_meta 0 max_int t) -> + (* If the tycon is not closed w.r.t real variables, we try *) + (* two different strategies *) + (* First strategy: we build an "inversion" predicate *) let sigma1,pred1 = build_inversion_problem loc env sigma tomatchs t in (* Optional second strategy: we abstract the tycon wrt to the dependencies *) let p2 = prepare_predicate_from_arsign_tycon env sigma loc tomatchs arsign t in - (* Third strategy: we take the type constraint as it is; of course we could *) - (* need something inbetween, abstracting some but not all of the dependencies *) - (* the "inversion" strategy deals with that but unification may not be *) - (* powerful enough so strategy 2 and 3 helps; moreover, inverting does not *) - (* work (yet) when a constructor has a type not precise enough for the inversion *) - (* see log message for details *) - let pred3 = lift (List.length (List.flatten arsign)) t in (match p2 with - | Some (sigma2,pred2) when not (Constr.equal pred2 pred3) -> - [sigma1, pred1; sigma2, pred2; sigma, pred3] - | _ -> - [sigma1, pred1; sigma, pred3]) + | Some (sigma2,pred2) -> [sigma1, pred1; sigma2, pred2] + | None -> [sigma1, pred1]) + | None, _ -> + (* No dependent type constraint, or no constraints at all: *) + (* we use two strategies *) + let sigma,t = match tycon with + | Some t -> sigma,t + | None -> + let sigma = Sigma.Unsafe.of_evar_map sigma in + let Sigma ((t, _), sigma, _) = + new_type_evar env sigma univ_flexible_alg ~src:(loc, Evar_kinds.CasesType false) in + let sigma = Sigma.to_evar_map sigma in + sigma, t + in + (* First strategy: we build an "inversion" predicate *) + let sigma1,pred1 = build_inversion_problem loc env sigma tomatchs t in + (* Second strategy: we use the evar or tycon as a non dependent pred *) + let pred2 = lift (List.length (List.flatten arsign)) t in + [sigma1, pred1; sigma, pred2] (* Some type annotation *) - | Some rtntyp -> + | Some rtntyp, _ -> (* We extract the signature of the arity *) let envar = List.fold_right push_rel_context arsign env in let sigma, newt = new_sort_variable univ_flexible_alg sigma in |