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feat(library/class_instance_resolution): add old type class resolution procedure back to be able to compile HoTT library

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Leonardo de Moura 2015-10-27 15:00:55 -07:00
parent 885393f4de
commit 50186e2db3
2 changed files with 372 additions and 2 deletions
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1
hott/init/funext.hlean
View file

@ -178,7 +178,6 @@ section
{ intro a, induction a with q p, induction q, esimp at *, induction p, reflexivity}
end
set_option class.conservative false
theorem nondep_funext_from_ua {A : Type} {B : Type}
: Π {f g : A → B}, f ~ g → f = g :=
(λ (f g : A → B) (p : f ~ g),

373
src/library/class_instance_resolution.cpp
View file

@ -24,6 +24,10 @@ Author: Leonardo de Moura
#include "library/choice_iterator.h"
#include "library/type_inference.h"
#include "library/class_instance_resolution.h"
// The following include files are need by the old type class resolution procedure
#include "util/lazy_list_fn.h"
#include "library/unifier.h"
#include "library/metavar_closure.h"
#ifndef LEAN_DEFAULT_CLASS_TRACE_INSTANCES
#define LEAN_DEFAULT_CLASS_TRACE_INSTANCES false
@ -1009,7 +1013,7 @@ static constraint mk_class_instance_root_cnstr(environment const & env, io_state
/** \brief Create a metavariable, and attach choice constraint for generating
solutions using class-instances
*/
pair<expr, constraint> mk_class_instance_elaborator(
pair<expr, constraint> mk_new_class_instance_elaborator(
environment const & env, io_state const & ios, local_context const & ctx,
name const & prefix, optional<name> const & suffix, bool use_local_instances,
bool is_strict, optional<expr> const & type, tag g, pos_info_provider const * pip) {
@ -1073,4 +1077,371 @@ void finalize_class_instance_resolution() {
delete g_class_instance_max_depth;
delete g_class_trans_instances;
}
/*
The rest of this module implements the old more powerful and *expensive* type class
resolution procedure. We still have it because the HoTT library contains
type class instances that require full-higher order unification to be solved.
Example:
definition is_equiv_tr [instance] [constructor] {A : Type} (P : A → Type) {x y : A}
(p : x = y) : (is_equiv (transport P p)) := ...
*/
/** \brief Context for handling class-instance metavariable choice constraint */
struct class_instance_context {
io_state m_ios;
name_generator m_ngen;
type_checker_ptr m_tc;
expr m_main_meta;
bool m_use_local_instances;
bool m_trace_instances;
bool m_conservative;
unsigned m_max_depth;
bool m_trans_instances;
char const * m_fname;
optional<pos_info> m_pos;
class_instance_context(environment const & env, io_state const & ios,
name const & prefix, bool use_local_instances):
m_ios(ios),
m_ngen(prefix),
m_use_local_instances(use_local_instances) {
m_fname = nullptr;
m_trace_instances = get_class_trace_instances(ios.get_options());
m_max_depth = get_class_instance_max_depth(ios.get_options());
m_conservative = true; // We removed the option class.conservative
m_trans_instances = get_class_trans_instances(ios.get_options());
m_tc = mk_class_type_checker(env, m_ngen.mk_child(), m_conservative);
options opts = m_ios.get_options();
opts = opts.update_if_undef(get_pp_purify_metavars_name(), false);
opts = opts.update_if_undef(get_pp_implicit_name(), true);
m_ios.set_options(opts);
}
environment const & env() const { return m_tc->env(); }
io_state const & ios() const { return m_ios; }
bool use_local_instances() const { return m_use_local_instances; }
type_checker & tc() const { return *m_tc; }
bool trace_instances() const { return m_trace_instances; }
void set_main_meta(expr const & meta) { m_main_meta = meta; }
expr const & get_main_meta() const { return m_main_meta; }
void set_pos(char const * fname, optional<pos_info> const & pos) {
m_fname = fname;
m_pos = pos;
}
optional<pos_info> const & get_pos() const { return m_pos; }
char const * get_file_name() const { return m_fname; }
unsigned get_max_depth() const { return m_max_depth; }
bool use_trans_instances() const { return m_trans_instances; }
};
static pair<expr, constraint>
mk_class_instance_elaborator(std::shared_ptr<class_instance_context> const & C, local_context const & ctx,
optional<expr> const & type, tag g, unsigned depth, bool use_globals);
/** \brief Choice function \c fn for synthesizing class instances.
The function \c fn produces a stream of alternative solutions for ?m.
In this case, \c fn will do the following:
1) if the elaborated type of ?m is a 'class' C, then the stream will start with
a) all local instances of class C (if elaborator.local_instances == true)
b) all global instances of class C
*/
struct class_instance_elaborator : public choice_iterator {
std::shared_ptr<class_instance_context> m_C;
local_context m_ctx;
expr m_meta;
// elaborated type of the metavariable
expr m_meta_type;
// local instances that should also be included in the
// class-instance resolution.
// This information is retrieved from the local context
list<expr> m_local_instances;
// global declaration names that are class instances.
// This information is retrieved using #get_class_instances.
list<name> m_trans_instances;
list<name> m_instances;
justification m_jst;
unsigned m_depth;
bool m_displayed_trace_header;
class_instance_elaborator(std::shared_ptr<class_instance_context> const & C, local_context const & ctx,
expr const & meta, expr const & meta_type,
list<expr> const & local_insts, list<name> const & trans_insts, list<name> const & instances,
justification const & j, unsigned depth):
choice_iterator(), m_C(C), m_ctx(ctx), m_meta(meta), m_meta_type(meta_type),
m_local_instances(local_insts), m_trans_instances(trans_insts), m_instances(instances), m_jst(j), m_depth(depth) {
if (m_depth > m_C->get_max_depth()) {
throw_class_exception("maximum class-instance resolution depth has been reached "
"(the limit can be increased by setting option 'class.instance_max_depth') "
"(the class-instance resolution trace can be visualized "
"by setting option 'class.trace_instances')",
C->get_main_meta());
}
m_displayed_trace_header = false;
}
constraints mk_constraints(constraint const & c, buffer<constraint> const & cs) {
return cons(c, to_list(cs.begin(), cs.end()));
}
void trace(expr const & t, expr const & r) {
if (!m_C->trace_instances())
return;
auto out = diagnostic(m_C->env(), m_C->ios());
if (!m_displayed_trace_header && m_depth == 0) {
if (auto fname = m_C->get_file_name()) {
out << fname << ":";
}
if (auto pos = m_C->get_pos()) {
out << pos->first << ":" << pos->second << ":";
}
out << " class-instance resolution trace" << endl;
m_displayed_trace_header = true;
}
for (unsigned i = 0; i < m_depth; i++)
out << " ";
if (m_depth > 0)
out << "[" << m_depth << "] ";
out << m_meta << " : " << t << " := " << r << endl;
}
optional<constraints> try_instance(expr const & inst, expr const & inst_type, bool use_globals) {
type_checker & tc = m_C->tc();
name_generator & ngen = m_C->m_ngen;
tag g = inst.get_tag();
try {
flet<local_context> scope(m_ctx, m_ctx);
buffer<expr> locals;
expr meta_type = m_meta_type;
while (true) {
meta_type = tc.whnf(meta_type).first;
if (!is_pi(meta_type))
break;
expr local = mk_local(ngen.next(), binding_name(meta_type),
binding_domain(meta_type), binding_info(meta_type));
m_ctx.add_local(local);
locals.push_back(local);
meta_type = instantiate(binding_body(meta_type), local);
}
expr type = inst_type;
expr r = inst;
buffer<constraint> cs;
while (true) {
type = tc.whnf(type).first;
if (!is_pi(type))
break;
expr arg;
if (binding_info(type).is_inst_implicit()) {
pair<expr, constraint> ac = mk_class_instance_elaborator(m_C, m_ctx, some_expr(binding_domain(type)),
g, m_depth+1, use_globals);
arg = ac.first;
cs.push_back(ac.second);
} else {
arg = m_ctx.mk_meta(m_C->m_ngen, some_expr(binding_domain(type)), g);
}
r = mk_app(r, arg, g);
type = instantiate(binding_body(type), arg);
}
r = Fun(locals, r);
trace(meta_type, r);
constraint c = mk_eq_cnstr(m_meta, r, m_jst);
return optional<constraints>(mk_constraints(c, cs));
} catch (exception &) {
return optional<constraints>();
}
}
optional<constraints> try_instance(name const & inst, bool use_globals) {
environment const & env = m_C->env();
if (auto decl = env.find(inst)) {
name_generator & ngen = m_C->m_ngen;
buffer<level> ls_buffer;
unsigned num_univ_ps = decl->get_num_univ_params();
for (unsigned i = 0; i < num_univ_ps; i++)
ls_buffer.push_back(mk_meta_univ(ngen.next()));
levels ls = to_list(ls_buffer.begin(), ls_buffer.end());
expr inst_cnst = copy_tag(m_meta, mk_constant(inst, ls));
expr inst_type = instantiate_type_univ_params(*decl, ls);
return try_instance(inst_cnst, inst_type, use_globals);
} else {
return optional<constraints>();
}
}
virtual optional<constraints> next() {
while (!empty(m_local_instances)) {
expr inst = head(m_local_instances);
m_local_instances = tail(m_local_instances);
if (!is_local(inst))
continue;
bool use_globals = true;
if (auto r = try_instance(inst, mlocal_type(inst), use_globals))
return r;
}
while (!empty(m_trans_instances)) {
bool use_globals = false;
name inst = head(m_trans_instances);
m_trans_instances = tail(m_trans_instances);
if (auto cs = try_instance(inst, use_globals))
return cs;
}
while (!empty(m_instances)) {
bool use_globals = true;
name inst = head(m_instances);
m_instances = tail(m_instances);
if (auto cs = try_instance(inst, use_globals))
return cs;
}
return optional<constraints>();
}
};
// Remarks:
// - we only use get_class_instances and get_class_derived_trans_instances when use_globals is true
static constraint mk_class_instance_cnstr(std::shared_ptr<class_instance_context> const & C,
local_context const & ctx, expr const & m, unsigned depth, bool use_globals) {
environment const & env = C->env();
justification j = mk_failed_to_synthesize_jst(env, m);
auto choice_fn = [=](expr const & meta, expr const & meta_type, substitution const &, name_generator const &) {
if (auto cls_name_it = is_ext_class(C->tc(), meta_type)) {
name cls_name = *cls_name_it;
list<expr> const & ctx_lst = ctx.get_data();
list<expr> local_insts;
if (C->use_local_instances())
local_insts = get_local_instances(C->tc(), ctx_lst, cls_name);
list<name> trans_insts, insts;
if (use_globals) {
if (depth == 0 && C->use_trans_instances())
trans_insts = get_class_derived_trans_instances(env, cls_name);
insts = get_class_instances(env, cls_name);
}
if (empty(local_insts) && empty(insts))
return lazy_list<constraints>(); // nothing to be done
// we are always strict with placeholders associated with classes
return choose(std::make_shared<class_instance_elaborator>(C, ctx, meta, meta_type, local_insts, trans_insts, insts, j, depth));
} else {
// do nothing, type is not a class...
return lazy_list<constraints>(constraints());
}
};
bool owner = false;
return mk_choice_cnstr(m, choice_fn, to_delay_factor(cnstr_group::Basic), owner, j);
}
static pair<expr, constraint> mk_class_instance_elaborator(std::shared_ptr<class_instance_context> const & C, local_context const & ctx,
optional<expr> const & type, tag g, unsigned depth, bool use_globals) {
expr m = ctx.mk_meta(C->m_ngen, type, g);
constraint c = mk_class_instance_cnstr(C, ctx, m, depth, use_globals);
return mk_pair(m, c);
}
static constraint mk_class_instance_root_cnstr(std::shared_ptr<class_instance_context> const & C, local_context const & _ctx,
expr const & m, bool is_strict, unifier_config const & cfg, delay_factor const & factor) {
environment const & env = C->env();
justification j = mk_failed_to_synthesize_jst(env, m);
auto choice_fn = [=](expr const & meta, expr const & meta_type, substitution const & s,
name_generator && ngen) {
environment const & env = C->env();
auto cls_name_it = is_ext_class(C->tc(), meta_type);
if (!cls_name_it) {
// do nothing, since type is not a class.
return lazy_list<constraints>(constraints());
}
local_context ctx = _ctx.instantiate(substitution(s));
pair<expr, justification> mj = update_meta(meta, s);
expr new_meta = mj.first;
justification new_j = mj.second;
unsigned depth = 0;
bool use_globals = true;
constraint c = mk_class_instance_cnstr(C, ctx, new_meta, depth, use_globals);
unifier_config new_cfg(cfg);
new_cfg.m_discard = false;
new_cfg.m_use_exceptions = false;
new_cfg.m_pattern = true;
new_cfg.m_kind = C->m_conservative ? unifier_kind::VeryConservative : unifier_kind::Liberal;
auto to_cnstrs_fn = [=](substitution const & subst, constraints const & cnstrs) -> constraints {
substitution new_s = subst;
// some constraints may have been postponed (example: universe level constraints)
constraints postponed = map(cnstrs,
[&](constraint const & c) {
// we erase internal justifications
return update_justification(c, mk_composite1(j, new_j));
});
metavar_closure cls(new_meta);
cls.add(meta_type);
constraints cs = cls.mk_constraints(new_s, new_j);
return append(cs, postponed);
};
auto no_solution_fn = [=]() {
if (is_strict)
return lazy_list<constraints>();
else
return lazy_list<constraints>(constraints());
};
unify_result_seq seq1 = unify(env, 1, &c, std::move(ngen), substitution(), new_cfg);
unify_result_seq seq2 = filter(seq1, [=](pair<substitution, constraints> const & p) {
substitution new_s = p.first;
expr result = new_s.instantiate(new_meta);
// We only keep complete solutions (modulo universe metavariables)
return !has_expr_metavar_relaxed(result);
});
if (try_multiple_instances(env, *cls_name_it)) {
lazy_list<constraints> seq3 = map2<constraints>(seq2, [=](pair<substitution, constraints> const & p) {
return to_cnstrs_fn(p.first, p.second);
});
if (is_strict) {
return seq3;
} else {
// make sure it does not fail by appending empty set of constraints
return append(seq3, lazy_list<constraints>(constraints()));
}
} else {
auto p = seq2.pull();
if (!p)
return no_solution_fn();
else
return lazy_list<constraints>(to_cnstrs_fn(p->first.first, p->first.second));
}
};
bool owner = false;
return mk_choice_cnstr(m, choice_fn, factor, owner, j);
}
/** \brief Create a metavariable, and attach choice constraint for generating
solutions using class-instances
*/
pair<expr, constraint> mk_old_class_instance_elaborator(
environment const & env, io_state const & ios, local_context const & ctx,
name const & prefix, optional<name> const & suffix, bool use_local_instances,
bool is_strict, optional<expr> const & type, tag g, unifier_config const & cfg,
pos_info_provider const * pip) {
auto C = std::make_shared<class_instance_context>(env, ios, prefix, use_local_instances);
expr m = ctx.mk_meta(C->m_ngen, suffix, type, g);
C->set_main_meta(m);
if (pip)
C->set_pos(pip->get_file_name(), pip->get_pos_info(m));
constraint c = mk_class_instance_root_cnstr(C, ctx, m, is_strict, cfg, delay_factor());
return mk_pair(m, c);
}
pair<expr, constraint> mk_class_instance_elaborator(
environment const & env, io_state const & ios, local_context const & ctx,
name const & prefix, optional<name> const & suffix, bool use_local_instances,
bool is_strict, optional<expr> const & type, tag g,
pos_info_provider const * pip) {
if (is_standard(env)) {
return mk_new_class_instance_elaborator(env, ios, ctx, prefix, suffix, use_local_instances,
is_strict, type, g, pip);
} else {
unifier_config cfg(ios.get_options(), true /* use exceptions */, true /* discard */);
return mk_old_class_instance_elaborator(env, ios, ctx, prefix, suffix, use_local_instances,
is_strict, type, g, cfg, pip);
}
}
}