feat(library/match): add 'local' backtracking
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
This commit is contained in:
Leonardo de Moura
parent
e6ffda0c51
commit
d1924097d5
2 changed files with 145 additions and 26 deletions
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@ -4,6 +4,7 @@ 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 <utility>
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#include "kernel/abstract.h"
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#include "kernel/instantiate.h"
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#include "kernel/for_each_fn.h"
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@ -37,17 +38,52 @@ class match_fn : public match_context {
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name_generator m_ngen;
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name_map<name> * m_name_subst;
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match_plugin const * m_plugin;
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buffer<std::pair<bool, unsigned>> m_stack;
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buffer<unsigned> m_scopes;
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void push() {
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m_scopes.push_back(m_stack.size());
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}
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void pop() {
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lean_assert(!m_scopes.empty());
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unsigned old_sz = m_scopes.back();
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while (m_stack.size() > old_sz) {
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auto p = m_stack.back();
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if (p.first)
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m_esubst[p.second] = none_expr();
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else
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m_lsubst[p.second] = none_level();
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m_stack.pop_back();
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}
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m_scopes.pop_back();
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}
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void keep() {
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m_scopes.back() = m_stack.size();
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}
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struct scope {
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match_fn & m;
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scope(match_fn & _m):m(_m) { m.push(); }
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~scope() { m.pop(); }
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void keep() { m.keep(); }
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};
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void _assign(expr const & p, expr const & t) {
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lean_assert(var_idx(p) < m_esubst.size());
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unsigned vidx = var_idx(p);
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unsigned sz = m_esubst.size();
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m_esubst[sz - vidx - 1] = t;
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unsigned i = sz - vidx - 1;
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m_stack.emplace_back(true, i);
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m_esubst[i] = t;
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}
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void _assign(level const & p, level const & l) {
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lean_assert(to_meta_idx(p) < m_lsubst.size());
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m_lsubst[to_meta_idx(p)] = l;
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unsigned i = to_meta_idx(p);
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m_stack.emplace_back(false, i);
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m_lsubst[i] = l;
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}
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void throw_exception() const {
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@ -97,7 +133,7 @@ class match_fn : public match_context {
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return (*m_plugin)(p, t, *this);
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}
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bool match_binding(expr p, expr t) {
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bool match_binding_core(expr p, expr t) {
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lean_assert(is_binding(p) && is_binding(t));
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buffer<expr> ls;
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expr_kind k = p.kind();
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@ -120,7 +156,18 @@ class match_fn : public match_context {
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return _match(p, t);
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}
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bool match_macro(expr const & p, expr const & t) {
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bool match_binding(expr const & p, expr const & t) {
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{
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scope s(*this);
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if (match_binding_core(p, t)) {
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s.keep();
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return true;
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}
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}
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return try_plugin(p, t);
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}
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bool match_macro_core(expr const & p, expr const & t) {
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if (macro_def(p) == macro_def(t) && macro_num_args(p) == macro_num_args(t)) {
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for (unsigned i = 0; i < macro_num_args(p); i++) {
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if (!_match(macro_arg(p, i), macro_arg(t, i)))
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@ -131,10 +178,32 @@ class match_fn : public match_context {
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return false;
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}
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bool match_app(expr const & p, expr const & t) {
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bool match_macro(expr const & p, expr const & t) {
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{
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scope s(*this);
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if (match_macro_core(p, t)) {
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s.keep();
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return true;
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}
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}
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return try_plugin(p, t);
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}
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bool match_app_core(expr const & p, expr const & t) {
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return match_core(app_fn(p), app_fn(t)) && _match(app_arg(p), app_arg(t));
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}
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bool match_app(expr const & p, expr const & t) {
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{
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scope s(*this);
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if (match_app_core(p, t)) {
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s.keep();
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return true;
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}
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}
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return try_plugin(p, t);
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}
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bool match_level_core(level const & p, level const & l) {
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if (p == l)
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return true;
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@ -146,16 +215,28 @@ class match_fn : public match_context {
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return false;
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case level_kind::Succ:
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return match_level(succ_of(p), succ_of(l));
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case level_kind::Max:
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return
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match_level(max_lhs(p), max_lhs(l)) &&
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match_level(max_rhs(p), max_rhs(l));
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case level_kind::IMax:
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return
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match_level(imax_lhs(p), imax_lhs(l)) &&
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match_level(imax_rhs(p), imax_rhs(l));
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case level_kind::Max: {
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scope s(*this);
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if (match_level(max_lhs(p), max_lhs(l)) && match_level(max_rhs(p), max_rhs(l))) {
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s.keep();
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return true;
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}
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break;
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}
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case level_kind::IMax: {
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scope s(*this);
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if (match_level(imax_lhs(p), imax_lhs(l)) && match_level(imax_rhs(p), imax_rhs(l))) {
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s.keep();
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return true;
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}
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break;
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}}
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}
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level p1 = normalize(p);
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level l1 = normalize(l);
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if (p1 != p || l1 != l)
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return match_level(p1, l1);
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else
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return false;
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}
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@ -182,6 +263,13 @@ class match_fn : public match_context {
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return true;
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}
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bool match_constant(expr const & p, expr const & t) {
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if (const_name(p) == const_name(t))
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return match_levels(const_levels(p), const_levels(t));
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else
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return try_plugin(p, t);
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}
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bool match_core(expr const & p, expr const & t) {
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if (p.kind() != t.kind())
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return try_plugin(p, t);
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@ -191,18 +279,15 @@ class match_fn : public match_context {
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case expr_kind::Var:
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lean_unreachable(); // LCOV_EXCL_LINE
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case expr_kind::Constant:
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if (const_name(p) == const_name(t))
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return match_levels(const_levels(p), const_levels(t));
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else
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return try_plugin(p, t);
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return match_constant(p, t);
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case expr_kind::Sort:
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return match_level(sort_level(p), sort_level(t));
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case expr_kind::Lambda: case expr_kind::Pi:
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return match_binding(p, t) || try_plugin(p, t);
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return match_binding(p, t);
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case expr_kind::Macro:
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return match_macro(p, t) || try_plugin(p, t);
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return match_macro(p, t);
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case expr_kind::App:
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return match_app(p, t) || try_plugin(p, t);
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return match_app(p, t);
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}
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lean_unreachable(); // LCOV_EXCL_LINE
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}
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34
tests/lean/run/match2.lean
Normal file
34
tests/lean/run/match2.lean
Normal file
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@ -0,0 +1,34 @@
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import data.nat
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using nat
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definition two1 : nat := 2
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definition two2 : nat := succ (succ (zero))
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definition f (x : nat) (y : nat) := y
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variable g : nat → nat → nat
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variables a b : nat
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(*
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local tc = type_checker_with_hints(get_env(), true)
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local plugin = whnf_match_plugin(tc)
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function tst_match(p, t)
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local r1, r2 = match(p, t, plugin)
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assert(r1)
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print("--------------")
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for i = 1, #r1 do
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print(" expr:#" .. i .. " := " .. tostring(r1[i]))
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end
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for i = 1, #r2 do
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print(" lvl:#" .. i .. " := " .. tostring(r2[i]))
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end
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end
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local f = Const("f")
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local g = Const("g")
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local a = Const("a")
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local b = Const("b")
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local x = mk_var(0)
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local p = g(x, f(x, a))
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local t = g(a, f(b, a))
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tst_match(p, t)
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tst_match(f(x, x), f(a, b))
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*)
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