lean2/src/library/definitional/util.cpp

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/*
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 "kernel/find_fn.h"
#include "kernel/instantiate.h"
#include "kernel/inductive/inductive.h"
namespace lean {
/** \brief Return true if environment has a constructor named \c c that returns
an element of the inductive datatype named \c I, and \c c must have \c nparams parameters.
*/
bool has_constructor(environment const & env, name const & c, name const & I, unsigned nparams) {
auto d = env.find(c);
if (!d || d->is_definition())
return false;
expr type = d->get_type();
unsigned i = 0;
while (is_pi(type)) {
i++;
type = binding_body(type);
}
if (i != nparams)
return false;
type = get_app_fn(type);
return is_constant(type) && const_name(type) == I;
}
bool has_unit_decls(environment const & env) {
return has_constructor(env, name{"unit", "star"}, "unit", 0);
}
bool has_eq_decls(environment const & env) {
return has_constructor(env, name{"eq", "refl"}, "eq", 2);
}
bool has_heq_decls(environment const & env) {
return has_constructor(env, name{"heq", "refl"}, "heq", 2);
}
bool has_prod_decls(environment const & env) {
return has_constructor(env, name{"prod", "mk"}, "prod", 4);
}
bool is_recursive_datatype(environment const & env, name const & n) {
optional<inductive::inductive_decls> decls = inductive::is_inductive_decl(env, n);
if (!decls)
return false;
for (inductive::inductive_decl const & decl : std::get<2>(*decls)) {
for (inductive::intro_rule const & intro : inductive::inductive_decl_intros(decl)) {
expr type = inductive::intro_rule_type(intro);
while (is_pi(type)) {
if (find(binding_domain(type), [&](expr const & e, unsigned) {
return is_constant(e) && const_name(e) == n; })) {
return true;
}
type = binding_body(type);
}
}
}
return false;
}
bool is_inductive_predicate(environment const & env, name const & n) {
if (!env.impredicative())
return false; // environment does not have Prop
if (!inductive::is_inductive_decl(env, n))
return false; // n is not inductive datatype
expr type = env.get(n).get_type();
while (is_pi(type)) {
type = binding_body(type);
}
return is_sort(type) && is_zero(sort_level(type));
}
expr to_telescope(name_generator & ngen, expr type, buffer<expr> & telescope, optional<binder_info> const & binfo) {
while (is_pi(type)) {
expr local;
if (binfo)
local = mk_local(ngen.next(), binding_name(type), binding_domain(type), *binfo);
else
local = mk_local(ngen.next(), binding_name(type), binding_domain(type), binder_info(type));
telescope.push_back(local);
type = instantiate(binding_body(type), local);
}
return type;
}
}