d0d75c0923
Now, eta and impredicativity are assumed to be always true. Motivation: the rest of the system assumes eta. Regarding impredicativity, we decided to support only the standard library.
49 lines
2.5 KiB
C++
49 lines
2.5 KiB
C++
/*
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Copyright (c) 2014 Microsoft Corporation. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Author: Leonardo de Moura
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*/
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#include "util/sstream.h"
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#include "kernel/environment.h"
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#include "kernel/instantiate.h"
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#include "kernel/type_checker.h"
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#include "library/module.h"
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#include "library/protected.h"
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#include "library/util.h"
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#include "library/aux_recursors.h"
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namespace lean {
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environment mk_induction_on(environment const & env, name const & n) {
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if (!inductive::is_inductive_decl(env, n))
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throw exception(sstream() << "error in 'induction_on' generation, '" << n << "' is not an inductive datatype");
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name rec_on_name(n, "rec_on");
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name induction_on_name(n, "induction_on");
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declaration rec_on_decl = env.get(rec_on_name);
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declaration ind_decl = env.get(n);
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unsigned rec_on_num_univs = rec_on_decl.get_num_univ_params();
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unsigned ind_num_univs = ind_decl.get_num_univ_params();
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environment new_env = env;
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if (rec_on_num_univs == ind_num_univs) {
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// easy case, induction_on is just an alias for rec_on
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certified_declaration cdecl = check(new_env,
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mk_definition_inferring_trusted(new_env, induction_on_name, rec_on_decl.get_univ_params(),
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rec_on_decl.get_type(), rec_on_decl.get_value(),
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reducibility_hints::mk_opaque()));
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new_env = module::add(new_env, cdecl);
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} else {
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level_param_names induction_on_univs = tail(rec_on_decl.get_univ_params());
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name from = head(rec_on_decl.get_univ_params());
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level to = mk_level_zero();
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expr induction_on_type = instantiate_univ_param(rec_on_decl.get_type(), from, to);
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expr induction_on_value = instantiate_univ_param(rec_on_decl.get_value(), from, to);
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certified_declaration cdecl = check(new_env,
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mk_definition_inferring_trusted(new_env, induction_on_name, induction_on_univs,
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induction_on_type, induction_on_value,
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reducibility_hints::mk_opaque()));
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new_env = add_aux_recursor(new_env, induction_on_name);
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new_env = module::add(new_env, cdecl);
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}
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return add_protected(new_env, induction_on_name);
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}
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}
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