feat(library/unifier): add flag for enabling/disabling expensive extensions in the unifier

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
This commit is contained in:
Leonardo de Moura 2014-07-31 16:38:18 -07:00
parent f57fc33442
commit de05c041c7
4 changed files with 261 additions and 17 deletions

View file

@ -28,6 +28,9 @@ namespace lean {
static name g_unifier_max_steps {"unifier", "max_steps"};
RegisterUnsignedOption(g_unifier_max_steps, LEAN_DEFAULT_UNIFIER_MAX_STEPS, "(unifier) maximum number of steps");
unsigned get_unifier_max_steps(options const & opts) { return opts.get_unsigned(g_unifier_max_steps, LEAN_DEFAULT_UNIFIER_MAX_STEPS); }
static name g_unifier_expensive {"unifier", "expensive"};
RegisterBoolOption(g_unifier_expensive, LEAN_DEFAULT_UNIFIER_EXPENSIVE, "(unifier) enable/disable expensive (and more complete) procedure");
bool get_unifier_expensive(options const & opts) { return opts.get_bool(g_unifier_expensive, LEAN_DEFAULT_UNIFIER_EXPENSIVE); }
/** \brief Return true iff \c [begin_locals, end_locals) contains \c local */
template<typename It> bool contains_local(expr const & local, It const & begin_locals, It const & end_locals) {
@ -253,6 +256,7 @@ struct unifier_fn {
bool m_use_exception; //!< True if we should throw an exception when there are no more solutions.
unsigned m_max_steps;
unsigned m_num_steps;
bool m_expensive;
bool m_first; //!< True if we still have to generate the first solution.
unsigned m_next_assumption_idx; //!< Next assumption index.
unsigned m_next_cidx; //!< Next constraint index.
@ -344,9 +348,9 @@ struct unifier_fn {
unifier_fn(environment const & env, unsigned num_cs, constraint const * cs,
name_generator const & ngen, substitution const & s,
bool use_exception, unsigned max_steps):
bool use_exception, unsigned max_steps, bool expensive):
m_env(env), m_ngen(ngen), m_subst(s), m_plugin(get_unifier_plugin(env)),
m_use_exception(use_exception), m_max_steps(max_steps), m_num_steps(0) {
m_use_exception(use_exception), m_max_steps(max_steps), m_num_steps(0), m_expensive(expensive) {
m_tc[0] = mk_type_checker_with_hints(env, m_ngen.mk_child(), false);
m_tc[1] = mk_type_checker_with_hints(env, m_ngen.mk_child(), true);
m_next_assumption_idx = 0;
@ -1471,12 +1475,14 @@ struct unifier_fn {
buffer<constraints> alts;
process_flex_rigid_core(lhs, rhs, j, relax, alts);
append_auxiliary_constraints(alts, to_list(aux.begin(), aux.end()));
expr rhs_whnf = whnf(rhs, j, relax, aux);
if (rhs_whnf != rhs) {
buffer<constraints> alts2;
process_flex_rigid_core(lhs, rhs_whnf, j, relax, alts2);
append_auxiliary_constraints(alts2, to_list(aux.begin(), aux.end()));
alts.append(alts2);
if (m_expensive) {
expr rhs_whnf = whnf(rhs, j, relax, aux);
if (rhs_whnf != rhs) {
buffer<constraints> alts2;
process_flex_rigid_core(lhs, rhs_whnf, j, relax, alts2);
append_auxiliary_constraints(alts2, to_list(aux.begin(), aux.end()));
alts.append(alts2);
}
}
if (alts.empty()) {
@ -1674,21 +1680,21 @@ lazy_list<substitution> unify(std::shared_ptr<unifier_fn> u) {
}
lazy_list<substitution> unify(environment const & env, unsigned num_cs, constraint const * cs, name_generator const & ngen,
bool use_exception, unsigned max_steps) {
return unify(std::make_shared<unifier_fn>(env, num_cs, cs, ngen, substitution(), use_exception, max_steps));
bool use_exception, unsigned max_steps, bool expensive) {
return unify(std::make_shared<unifier_fn>(env, num_cs, cs, ngen, substitution(), use_exception, max_steps, expensive));
}
lazy_list<substitution> unify(environment const & env, unsigned num_cs, constraint const * cs, name_generator const & ngen,
bool use_exception, options const & o) {
return unify(env, num_cs, cs, ngen, use_exception, get_unifier_max_steps(o));
return unify(env, num_cs, cs, ngen, use_exception, get_unifier_max_steps(o), get_unifier_expensive(o));
}
lazy_list<substitution> unify(environment const & env, expr const & lhs, expr const & rhs, name_generator const & ngen,
bool relax, substitution const & s, unsigned max_steps) {
bool relax, substitution const & s, unsigned max_steps, bool expensive) {
substitution new_s = s;
expr _lhs = new_s.instantiate(lhs);
expr _rhs = new_s.instantiate(rhs);
auto u = std::make_shared<unifier_fn>(env, 0, nullptr, ngen, new_s, false, max_steps);
auto u = std::make_shared<unifier_fn>(env, 0, nullptr, ngen, new_s, false, max_steps, expensive);
if (!u->m_tc[relax]->is_def_eq(_lhs, _rhs))
return lazy_list<substitution>();
else
@ -1697,7 +1703,7 @@ lazy_list<substitution> unify(environment const & env, expr const & lhs, expr co
lazy_list<substitution> unify(environment const & env, expr const & lhs, expr const & rhs, name_generator const & ngen,
bool relax, substitution const & s, options const & o) {
return unify(env, lhs, rhs, ngen, relax, s, get_unifier_max_steps(o));
return unify(env, lhs, rhs, ngen, relax, s, get_unifier_max_steps(o), get_unifier_expensive(o));
}
static int unify_simple(lua_State * L) {

View file

@ -19,6 +19,10 @@ Author: Leonardo de Moura
#define LEAN_DEFAULT_UNIFIER_MAX_STEPS 10000
#endif
#ifndef LEAN_DEFAULT_UNIFIER_EXPENSIVE
#define LEAN_DEFAULT_UNIFIER_EXPENSIVE false
#endif
namespace lean {
unsigned get_unifier_max_steps(options const & opts);
bool get_unifier_unfold_opaque(options const & opts);
@ -37,11 +41,11 @@ unify_status unify_simple(substitution & s, level const & lhs, level const & rhs
unify_status unify_simple(substitution & s, constraint const & c);
lazy_list<substitution> unify(environment const & env, unsigned num_cs, constraint const * cs, name_generator const & ngen,
bool use_exception = true, unsigned max_steps = LEAN_DEFAULT_UNIFIER_MAX_STEPS);
bool use_exception = true, unsigned max_steps = LEAN_DEFAULT_UNIFIER_MAX_STEPS, bool expensive = LEAN_DEFAULT_UNIFIER_EXPENSIVE);
lazy_list<substitution> unify(environment const & env, unsigned num_cs, constraint const * cs, name_generator const & ngen,
bool use_exception, options const & o);
lazy_list<substitution> unify(environment const & env, expr const & lhs, expr const & rhs, name_generator const & ngen, bool relax_main_opaque,
substitution const & s = substitution(), unsigned max_steps = LEAN_DEFAULT_UNIFIER_MAX_STEPS);
substitution const & s = substitution(), unsigned max_steps = LEAN_DEFAULT_UNIFIER_MAX_STEPS, bool expensive = LEAN_DEFAULT_UNIFIER_MAX_STEPS);
lazy_list<substitution> unify(environment const & env, expr const & lhs, expr const & rhs, name_generator const & ngen,
bool relax_main_opaque, substitution const & s, options const & o);

View file

@ -11,7 +11,7 @@
import nat
using nat eq_proofs
set_option unifier.expensive true
inductive list (T : Type) : Type :=
| nil {} : list T
| cons : T → list T → list T

View file

@ -0,0 +1,234 @@
----------------------------------------------------------------------------------------------------
--- Copyright (c) 2014 Parikshit Khanna. All rights reserved.
--- Released under Apache 2.0 license as described in the file LICENSE.
--- Authors: Parikshit Khanna, Jeremy Avigad
----------------------------------------------------------------------------------------------------
-- Theory list
-- ===========
--
-- Basic properties of lists.
import tactic
import nat
-- import congr
set_option unifier.expensive true
using nat
-- using congr
using eq_proofs
namespace list
-- Type
-- ----
inductive list (T : Type) : Type :=
| nil {} : list T
| cons : T → list T → list T
infix `::` : 65 := cons
section
variable {T : Type}
theorem list_induction_on {P : list T → Prop} (l : list T) (Hnil : P nil)
(Hind : forall x : T, forall l : list T, forall H : P l, P (cons x l)) : P l :=
list_rec Hnil Hind l
theorem list_cases_on {P : list T → Prop} (l : list T) (Hnil : P nil)
(Hcons : forall x : T, forall l : list T, P (cons x l)) : P l :=
list_induction_on l Hnil (take x l IH, Hcons x l)
notation `[` l:(foldr `,` (h t, cons h t) nil) `]` := l
-- Concat
-- ------
definition concat (s t : list T) : list T :=
list_rec t (fun x : T, fun l : list T, fun u : list T, cons x u) s
infixl `++` : 65 := concat
theorem nil_concat (t : list T) : nil ++ t = t := refl _
theorem cons_concat (x : T) (s t : list T) : (x :: s) ++ t = x :: (s ++ t) := refl _
theorem concat_nil (t : list T) : t ++ nil = t :=
list_induction_on t (refl _)
(take (x : T) (l : list T) (H : concat l nil = l),
H ▸ (refl (cons x (concat l nil))))
theorem concat_nil2 (t : list T) : t ++ nil = t :=
list_induction_on t (refl _)
(take (x : T) (l : list T) (H : concat l nil = l),
-- H ▸ (refl (cons x (concat l nil))))
H ▸ (refl (concat (cons x l) nil)))
theorem concat_assoc (s t u : list T) : s ++ t ++ u = s ++ (t ++ u) :=
list_induction_on s (refl _)
(take x l,
assume H : concat (concat l t) u = concat l (concat t u),
H ▸ refl _)
theorem concat_assoc2 (s t u : list T) : s ++ t ++ u = s ++ (t ++ u) :=
list_induction_on s (refl _)
(take x l,
assume H : concat (concat l t) u = concat l (concat t u),
calc concat (concat (cons x l) t) u = cons x (concat (concat l t) u) : refl _
... = concat (cons x l) (concat t u) : { H })
theorem concat_assoc3 (s t u : list T) : s ++ t ++ u = s ++ (t ++ u) :=
list_induction_on s (refl _)
(take x l,
assume H : concat (concat l t) u = concat l (concat t u),
calc concat (concat (cons x l) t) u = cons x (concat l (concat t u)) : { H }
... = concat (cons x l) (concat t u) : refl _)
theorem concat_assoc4 (s t u : list T) : s ++ t ++ u = s ++ (t ++ u) :=
list_induction_on s (refl _)
(take x l,
assume H : concat (concat l t) u = concat l (concat t u),
calc
concat (concat (cons x l) t) u = cons x (concat (concat l t) u) : refl _
... = cons x (concat l (concat t u)) : { H }
... = concat (cons x l) (concat t u) : refl _)
-- Length
-- ------
definition length : list T → := list_rec 0 (fun x l m, succ m)
-- TODO: cannot replace zero by 0
theorem length_nil : length (@nil T) = zero := refl _
theorem length_cons (x : T) (t : list T) : length (x :: t) = succ (length t) := refl _
theorem length_concat (s t : list T) : length (s ++ t) = length s + length t :=
list_induction_on s
(calc
length (concat nil t) = length t : refl _
... = zero + length t : {symm (add_zero_left (length t))}
... = length (@nil T) + length t : refl _)
(take x s,
assume H : length (concat s t) = length s + length t,
calc
length (concat (cons x s) t ) = succ (length (concat s t)) : refl _
... = succ (length s + length t) : { H }
... = succ (length s) + length t : {symm (add_succ_left _ _)}
... = length (cons x s) + length t : refl _)
-- Reverse
-- -------
definition reverse : list T → list T := list_rec nil (fun x l r, r ++ [x])
theorem reverse_nil : reverse (@nil T) = nil := refl _
theorem reverse_cons (x : T) (l : list T) : reverse (x :: l) = (reverse l) ++ (cons x nil) := refl _
-- opaque_hint (hiding reverse)
theorem reverse_concat (s t : list T) : reverse (s ++ t) = (reverse t) ++ (reverse s) :=
list_induction_on s
(calc
reverse (concat nil t) = reverse t : { nil_concat _ }
... = concat (reverse t) nil : symm (concat_nil _)
... = concat (reverse t) (reverse nil) : {symm (reverse_nil)})
(take x l,
assume H : reverse (concat l t) = concat (reverse t) (reverse l),
calc
reverse (concat (cons x l) t) = concat (reverse (concat l t)) (cons x nil) : refl _
... = concat (concat (reverse t) (reverse l)) (cons x nil) : { H }
... = concat (reverse t) (concat (reverse l) (cons x nil)) : concat_assoc _ _ _
... = concat (reverse t) (reverse (cons x l)) : refl _)
-- -- add_rewrite length_nil length_cons
theorem reverse_reverse (l : list T) : reverse (reverse l) = l :=
list_induction_on l (refl _)
(take x l',
assume H: reverse (reverse l') = l',
show reverse (reverse (cons x l')) = cons x l', from
calc
reverse (reverse (cons x l')) =
concat (reverse (cons x nil)) (reverse (reverse l')) : {reverse_concat _ _}
... = cons x l' : {H})
-- Append
-- ------
-- TODO: define reverse from append
definition append (x : T) : list T → list T := list_rec (x :: nil) (fun y l l', y :: l')
theorem append_nil (x : T) : append x nil = [x] := refl _
theorem append_cons (x : T) (y : T) (l : list T) : append x (y :: l) = y :: (append x l) := refl _
theorem append_eq_concat (x : T) (l : list T) : append x l = l ++ [x] :=
list_induction_on l (refl _)
(take y l,
assume P : append x l = concat l [x],
P ▸ refl _)
set_option unifier.expensive false
theorem append_eq_reverse_cons (x : T) (l : list T) : append x l = reverse (x :: reverse l) :=
list_induction_on l
(calc
append x nil = [x] : (refl _)
... = concat nil [x] : {symm (nil_concat _)}
... = concat (reverse nil) [x] : {symm (reverse_nil)}
... = reverse [x] : {symm (reverse_cons _ _)}
... = reverse (x :: (reverse nil)) : {symm (reverse_nil)})
(take y l',
assume H : append x l' = reverse (x :: reverse l'),
calc
append x (y :: l') = (y :: l') ++ [ x ] : append_eq_concat _ _
... = concat (reverse (reverse (y :: l'))) [ x ] : {symm (reverse_reverse _)}
... = reverse (x :: (reverse (y :: l'))) : refl _)
exit
-- Head and tail
-- -------------
definition head (x0 : T) : list T → T := list_rec x0 (fun x l h, x)
theorem head_nil (x0 : T) : head x0 (@nil T) = x0 := refl _
theorem head_cons (x : T) (x0 : T) (t : list T) : head x0 (x :: t) = x := refl _
theorem head_concat (s t : list T) (x0 : T) : s ≠ nil → (head x0 (s ++ t) = head x0 s) :=
list_cases_on s
(take H : nil ≠ nil, absurd_elim (head x0 (concat nil t) = head x0 nil) (refl nil) H)
(take x s,
take H : cons x s ≠ nil,
calc
head x0 (concat (cons x s) t) = head x0 (cons x (concat s t)) : {cons_concat _ _ _}
... = x : {head_cons _ _ _}
... = head x0 (cons x s) : {symm ( head_cons x x0 s)})
definition tail : list T → list T := list_rec nil (fun x l b, l)
theorem tail_nil : tail (@nil T) = nil := refl _
theorem tail_cons (x : T) (l : list T) : tail (cons x l) = l := refl _
theorem cons_head_tail (x0 : T) (l : list T) : l ≠ nil → (head x0 l) :: (tail l) = l :=
list_cases_on l
(assume H : nil ≠ nil, absurd_elim _ (refl _) H)
(take x l, assume H : cons x l ≠ nil, refl _)
-- List membership
-- ---------------
definition mem (x : T) : list T → Prop := list_rec false (fun y l H, x = y H)
infix `∈` : 50 := mem
theorem mem_nil (x : T) : mem x nil ↔ false := iff_refl _
theorem mem_cons (x : T) (y : T) (l : list T) : mem x (cons y l) ↔ (x = y mem x l) := iff_refl _