C++ environment::impredicative方法代码示例

environment mk_projections(environment const & env, name const & n, buffer<name> const & proj_names,
                           implicit_infer_kind infer_k, bool inst_implicit) {
    // Given an inductive datatype C A (where A represent parameters)
    //   intro : Pi A (x_1 : B_1[A]) (x_2 : B_2[A, x_1]) ..., C A
    //
    // we generate projections of the form
    //   proj_i A (c : C A) : B_i[A, (proj_1 A n), ..., (proj_{i-1} A n)]
    //     C.rec A (fun (x : C A), B_i[A, ...]) (fun (x_1 ... x_n), x_i) c
    auto p = get_nparam_intro_rule(env, n);
    name_generator ngen;
    unsigned nparams             = p.first;
    inductive::intro_rule intro  = p.second;
    expr intro_type              = inductive::intro_rule_type(intro);
    name rec_name                = inductive::get_elim_name(n);
    declaration ind_decl         = env.get(n);
    if (env.impredicative() && is_prop(ind_decl.get_type()))
        throw exception(sstream() << "projection generation, '" << n << "' is a proposition");
    declaration rec_decl         = env.get(rec_name);
    level_param_names lvl_params = ind_decl.get_univ_params();
    levels lvls                  = param_names_to_levels(lvl_params);
    buffer<expr> params; // datatype parameters
    for (unsigned i = 0; i < nparams; i++) {
        if (!is_pi(intro_type))
            throw_ill_formed(n);
        expr param = mk_local(ngen.next(), binding_name(intro_type), binding_domain(intro_type), binder_info());
        intro_type = instantiate(binding_body(intro_type), param);
        params.push_back(param);
    }
    expr C_A                     = mk_app(mk_constant(n, lvls), params);
    binder_info c_bi             = inst_implicit ? mk_inst_implicit_binder_info() : binder_info();
    expr c                       = mk_local(ngen.next(), name("c"), C_A, c_bi);
    buffer<expr> intro_type_args; // arguments that are not parameters
    expr it = intro_type;
    while (is_pi(it)) {
        expr local = mk_local(ngen.next(), binding_name(it), binding_domain(it), binding_info(it));
        intro_type_args.push_back(local);
        it = instantiate(binding_body(it), local);
    }
    buffer<expr> projs; // projections generated so far
    unsigned i = 0;
    environment new_env = env;
    for (name const & proj_name : proj_names) {
        if (!is_pi(intro_type))
            throw exception(sstream() << "generating projection '" << proj_name << "', '"
                            << n << "' does not have sufficient data");
        expr result_type   = binding_domain(intro_type);
        buffer<expr> proj_args;
        proj_args.append(params);
        proj_args.push_back(c);
        expr type_former   = Fun(c, result_type);
        expr minor_premise = Fun(intro_type_args, mk_var(intro_type_args.size() - i - 1));
        expr major_premise = c;
        type_checker tc(new_env);
        level l            = sort_level(tc.ensure_sort(tc.infer(result_type).first).first);
        levels rec_lvls    = append(to_list(l), lvls);
        expr rec           = mk_constant(rec_name, rec_lvls);
        buffer<expr> rec_args;
        rec_args.append(params);
        rec_args.push_back(type_former);
        rec_args.push_back(minor_premise);
        rec_args.push_back(major_premise);
        expr rec_app      = mk_app(rec, rec_args);
        expr proj_type    = Pi(proj_args, result_type);
        proj_type         = infer_implicit_params(proj_type, nparams, infer_k);
        expr proj_val     = Fun(proj_args, rec_app);
        bool opaque       = false;
        bool use_conv_opt = false;
        declaration new_d = mk_definition(env, proj_name, lvl_params, proj_type, proj_val,
                                          opaque, rec_decl.get_module_idx(), use_conv_opt);
        new_env = module::add(new_env, check(new_env, new_d));
        new_env = set_reducible(new_env, proj_name, reducible_status::Reducible);
        new_env = add_unfold_c_hint(new_env, proj_name, nparams);
        new_env = save_projection_info(new_env, proj_name, inductive::intro_rule_name(intro), nparams, i, inst_implicit);
        expr proj         = mk_app(mk_app(mk_constant(proj_name, lvls), params), c);
        intro_type        = instantiate(binding_body(intro_type), proj);
        i++;
    }
    return new_env;
}

optional<environment> mk_no_confusion_type(environment const & env, name const & n) {
    optional<inductive::inductive_decls> decls = inductive::is_inductive_decl(env, n);
    if (!decls)
        throw exception(sstream() << "error in 'no_confusion' generation, '" << n << "' is not an inductive datatype");
    if (is_inductive_predicate(env, n))
        return optional<environment>(); // type is a proposition
    name_generator ngen;
    unsigned nparams       = std::get<1>(*decls);
    declaration ind_decl   = env.get(n);
    declaration cases_decl = env.get(name(n, "cases_on"));
    level_param_names lps  = cases_decl.get_univ_params();
    level  rlvl            = mk_param_univ(head(lps));
    levels ilvls           = param_names_to_levels(tail(lps));
    if (length(ilvls) != length(ind_decl.get_univ_params()))
        return optional<environment>(); // type does not have only a restricted eliminator
    expr ind_type          = instantiate_type_univ_params(ind_decl, ilvls);
    name eq_name("eq");
    name heq_name("heq");
    // All inductive datatype parameters and indices are arguments
    buffer<expr> args;
    ind_type = to_telescope(ngen, ind_type, args, some(mk_implicit_binder_info()));
    if (!is_sort(ind_type) || args.size() < nparams)
        throw_corrupted(n);
    lean_assert(!(env.impredicative() && is_zero(sort_level(ind_type))));
    unsigned nindices      = args.size() - nparams;
    // Create inductive datatype
    expr I = mk_app(mk_constant(n, ilvls), args);
    // Add (P : Type)
    expr P = mk_local(ngen.next(), "P", mk_sort(rlvl), binder_info());
    args.push_back(P);
    // add v1 and v2 elements of the inductive type
    expr v1 = mk_local(ngen.next(), "v1", I, binder_info());
    expr v2 = mk_local(ngen.next(), "v2", I, binder_info());
    args.push_back(v1);
    args.push_back(v2);
    expr R  = mk_sort(rlvl);
    name no_confusion_type_name{n, "no_confusion_type"};
    expr no_confusion_type_type = Pi(args, R);
    // Create type former
    buffer<expr> type_former_args;
    for (unsigned i = nparams; i < nparams + nindices; i++)
        type_former_args.push_back(args[i]);
    type_former_args.push_back(v1);
    expr type_former = Fun(type_former_args, R);
    // Create cases_on
    levels clvls   = levels(mk_succ(rlvl), ilvls);
    expr cases_on  = mk_app(mk_app(mk_constant(cases_decl.get_name(), clvls), nparams, args.data()), type_former);
    cases_on       = mk_app(cases_on, nindices, args.data() + nparams);
    expr cases_on1 = mk_app(cases_on, v1);
    expr cases_on2 = mk_app(cases_on, v2);
    type_checker tc(env);
    expr t1        = tc.infer(cases_on1).first;
    expr t2        = tc.infer(cases_on2).first;
    buffer<expr> outer_cases_on_args;
    unsigned idx1 = 0;
    while (is_pi(t1)) {
        buffer<expr> minor1_args;
        expr minor1 = to_telescope(tc, binding_domain(t1), minor1_args);
        expr curr_t2  = t2;
        buffer<expr> inner_cases_on_args;
        unsigned idx2 = 0;
        while (is_pi(curr_t2)) {
            buffer<expr> minor2_args;
            expr minor2 = to_telescope(tc, binding_domain(curr_t2), minor2_args);
            if (idx1 != idx2) {
                // infeasible case, constructors do not match
                inner_cases_on_args.push_back(Fun(minor2_args, P));
            } else {
                if (minor1_args.size() != minor2_args.size())
                    throw_corrupted(n);
                buffer<expr> rtype_hyp;
                // add equalities
                for (unsigned i = 0; i < minor1_args.size(); i++) {
                    expr lhs      = minor1_args[i];
                    expr rhs      = minor2_args[i];
                    expr lhs_type = mlocal_type(lhs);
                    expr rhs_type = mlocal_type(rhs);
                    level l       = sort_level(tc.ensure_type(lhs_type).first);
                    expr h_type;
                    if (tc.is_def_eq(lhs_type, rhs_type).first) {
                        h_type = mk_app(mk_constant(eq_name, to_list(l)), lhs_type, lhs, rhs);
                    } else {
                        h_type = mk_app(mk_constant(heq_name, to_list(l)), lhs_type, lhs, rhs_type, rhs);
                    }
                    rtype_hyp.push_back(mk_local(ngen.next(), local_pp_name(lhs).append_after("_eq"), h_type, binder_info()));
                }
                inner_cases_on_args.push_back(Fun(minor2_args, mk_arrow(Pi(rtype_hyp, P), P)));
            }
            idx2++;
            curr_t2 = binding_body(curr_t2);
        }
        outer_cases_on_args.push_back(Fun(minor1_args, mk_app(cases_on2, inner_cases_on_args)));
        idx1++;
        t1 = binding_body(t1);
    }
    expr no_confusion_type_value = Fun(args, mk_app(cases_on1, outer_cases_on_args));

    bool opaque       = false;
    bool use_conv_opt = true;
    declaration new_d = mk_definition(env, no_confusion_type_name, lps, no_confusion_type_type, no_confusion_type_value,
//.........这里部分代码省略.........