lean4-htt/src/library/constructions/rec_on.cpp

63 lines
2.6 KiB
C++

/*
Copyright (c) 2014 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Leonardo de Moura
*/
#include "runtime/sstream.h"
#include "kernel/environment.h"
#include "kernel/instantiate.h"
#include "kernel/abstract.h"
#include "kernel/inductive.h"
#include "library/reducible.h"
#include "library/protected.h"
#include "library/suffixes.h"
#include "library/aux_recursors.h"
#include "library/constructions/util.h"
namespace lean {
environment mk_rec_on(environment const & env, name const & n) {
constant_info ind_info = env.get(n);
if (!ind_info.is_inductive())
throw exception(sstream() << "error in '" << g_rec_on << "' generation, '" << n << "' is not an inductive datatype");
name_generator ngen = mk_constructions_name_generator();
local_ctx lctx;
name rec_on_name(n, g_rec_on);
constant_info rec_info = env.get(mk_rec_name(n));
recursor_val rec_val = rec_info.to_recursor_val();
buffer<expr> locals;
expr rec_type = rec_info.get_type();
while (is_pi(rec_type)) {
expr local = lctx.mk_local_decl(ngen, binding_name(rec_type), binding_domain(rec_type), binding_info(rec_type));
rec_type = instantiate(binding_body(rec_type), local);
locals.push_back(local);
}
// locals order
// As Cs minor_premises indices major-premise
// new_locals order
// As Cs indices major-premise minor-premises
buffer<expr> new_locals;
unsigned num_indices = rec_val.get_nindices();
unsigned num_minors = rec_val.get_nminors();
unsigned AC_sz = locals.size() - num_minors - num_indices - 1;
for (unsigned i = 0; i < AC_sz; i++)
new_locals.push_back(locals[i]);
for (unsigned i = 0; i < num_indices + 1; i++)
new_locals.push_back(locals[AC_sz + num_minors + i]);
for (unsigned i = 0; i < num_minors; i++)
new_locals.push_back(locals[AC_sz + i]);
expr rec_on_type = lctx.mk_pi(new_locals, rec_type);
levels ls = lparams_to_levels(rec_info.get_lparams());
expr rec = mk_constant(rec_info.get_name(), ls);
expr rec_on_val = lctx.mk_lambda(new_locals, mk_app(rec, locals));
environment new_env = env.add(mk_definition_inferring_unsafe(env, rec_on_name, rec_info.get_lparams(),
rec_on_type, rec_on_val, reducibility_hints::mk_abbreviation()));
new_env = set_reducible(new_env, rec_on_name, reducible_status::Reducible, true);
new_env = add_aux_recursor(new_env, rec_on_name);
return add_protected(new_env, rec_on_name);
}
}