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feat(library/elaborator): provide the metavar_env to instantiate and lift_free_vars in the elaborator, it will minimize the number of local_entries needed

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The modifications started at commit 1852c86948 made a big difference. For example, before these changes test tests/lean/implicit7.lean generated complicated constraints such as:

[x : Type; a : ?M::29[inst:1 ?M::0[lift:0:1]] x] ⊢ Pi B : Type, (Pi _ : x, (Pi _ : (?M::35[inst:0 #0, inst:1 #2, inst:2 #4, inst:3 #6, inst:5 #5, inst:6 #7, inst:7 #9, inst:9 #9, inst:10 #11, inst:13 ?M::0[lift:0:13]] x a B _), (?M::36[inst:1 #1, inst:2 #3, inst:3 #5, inst:4 #7, inst:6 #6, inst:7 #8, inst:8 #10, inst:10 #10, inst:11 #12, inst:14 ?M::0[lift:0:14]] x a B _ _))) ≈
?M::22 x a

After the changes, only very simple constraints are generated. The most complicated one is:

[] ⊢ Pi a : ?M::0, (Pi B : Type, (Pi _ : ?M::0, (Pi _ : B, ?M::0))) ≈ Pi x : ?M::17, ?M::18

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
This commit is contained in:
Leonardo de Moura 2013-12-14 15:55:12 -08:00
parent 70b7e519f8
commit 160a8379ef
2 changed files with 16 additions and 12 deletions
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8
src/frontends/lean/frontend_elaborator.cpp
View file

@ -145,6 +145,10 @@ class frontend_elaborator::imp {
imp & m_ref;
preprocessor(imp & r):m_ref(r) {}
expr instantiate(expr const & e, expr const & v) {
return ::lean::instantiate(e, v, m_ref.m_menv);
}
virtual expr visit_constant(expr const & e, context const & ctx) {
if (is_placeholder(e)) {
expr m = m_ref.m_menv->mk_metavar(ctx, visit(const_type(e), ctx));
@ -249,7 +253,7 @@ class frontend_elaborator::imp {
num_skipped_args++;
}
}
f_t = some_expr(::lean::instantiate(abst_body(*f_t), args[i]));
f_t = some_expr(instantiate(abst_body(*f_t), args[i]));
}
}
if (i == num_args) {
@ -372,7 +376,7 @@ class frontend_elaborator::imp {
}
new_args.push_back(new_a);
if (f_t)
f_t = some_expr(::lean::instantiate(abst_body(*f_t), new_a));
f_t = some_expr(instantiate(abst_body(*f_t), new_a));
}
return mk_app(new_args);
}

20
src/library/elaborator/elaborator.cpp
View file

@ -454,7 +454,7 @@ class elaborator::imp {
// in the assign(a, b, c) branch above.
justification new_jst(new normalize_justification(c));
expr new_a = pop_meta_context(a);
expr new_b = lift_free_vars(b, me.s(), 1);
expr new_b = lift_free_vars(b, me.s(), 1, m_state.m_menv);
context new_ctx = ctx.insert_at(me.s(), g_x_name, Type()); // insert a dummy at position s
if (!is_lhs)
swap(new_a, new_b);
@ -522,7 +522,7 @@ class elaborator::imp {
/** \brief Unfold let-expression */
void process_let(expr & a) {
if (is_let(a))
a = instantiate(let_body(a), let_value(a));
a = instantiate(let_body(a), let_value(a), m_state.m_menv);
}
/** \brief Replace variables by their definition if the context contains it. */
@ -788,7 +788,7 @@ class elaborator::imp {
// Assign f_a <- fun (x_1 : T_1) ... (x_{num_a} : T_{num_a}), f_b (h_1 x_1 ... x_{num_a}) ... (h_{num_b} x_1 ... x_{num_a})
// New constraints (h_i a_1 ... a_{num_a}) == arg(b, i)
buffer<expr> imitation_args; // arguments for the imitation
imitation_args.push_back(lift_free_vars(f_b, 0, num_a - 1));
imitation_args.push_back(lift_free_vars(f_b, 0, num_a - 1, new_state.m_menv));
for (unsigned i = 1; i < num_b; i++) {
// Remark: h_ctx is "ctx, (x_{num_a} : T_{num_a}) ... (x_1 : T_1)" because h_i is inside of the lambda
expr h_i = new_state.m_menv->mk_metavar(h_ctx);
@ -822,7 +822,7 @@ class elaborator::imp {
} else {
// "Dumb imitation" aka the constant function
// Assign f_a <- fun (x_1 : T_1) ... (x_{num_a} : T_{num_a}), b
imitation = mk_lambda(arg_types, lift_free_vars(b, 0, num_a - 1));
imitation = mk_lambda(arg_types, lift_free_vars(b, 0, num_a - 1, new_state.m_menv));
}
push_new_eq_constraint(new_state.m_queue, ctx, f_a, imitation, new_assumption);
new_cs->push_back(new_state, new_assumption);
@ -912,7 +912,7 @@ class elaborator::imp {
for (unsigned j = 1; j < num_b; j++) {
expr h_j = new_state.m_menv->mk_metavar(ctx);
imitation_args.push_back(h_j);
push_new_eq_constraint(new_state.m_queue, ctx, h_j, lift_free_vars(arg(b, j), i, 1), new_assumption);
push_new_eq_constraint(new_state.m_queue, ctx, h_j, lift_free_vars(arg(b, j), i, 1, new_state.m_menv), new_assumption);
}
imitation = mk_app(imitation_args);
} else if (is_eq(b)) {
@ -921,20 +921,20 @@ class elaborator::imp {
expr h_1 = new_state.m_menv->mk_metavar(ctx);
expr h_2 = new_state.m_menv->mk_metavar(ctx);
imitation = mk_eq(h_1, h_2);
push_new_eq_constraint(new_state.m_queue, ctx, h_1, lift_free_vars(eq_lhs(b), i, 1), new_assumption);
push_new_eq_constraint(new_state.m_queue, ctx, h_2, lift_free_vars(eq_rhs(b), i, 1), new_assumption);
push_new_eq_constraint(new_state.m_queue, ctx, h_1, lift_free_vars(eq_lhs(b), i, 1, new_state.m_menv), new_assumption);
push_new_eq_constraint(new_state.m_queue, ctx, h_2, lift_free_vars(eq_rhs(b), i, 1, new_state.m_menv), new_assumption);
} else if (is_abstraction(b)) {
// Lambdas and Pis
// Imitation for Lambdas and Pis, b == Fun(x:T) B
// mname <- Fun (x:?h_1) ?h_2
expr h_1 = new_state.m_menv->mk_metavar(ctx);
push_new_eq_constraint(new_state.m_queue, ctx, h_1, lift_free_vars(abst_domain(b), i, 1), new_assumption);
push_new_eq_constraint(new_state.m_queue, ctx, h_1, lift_free_vars(abst_domain(b), i, 1, new_state.m_menv), new_assumption);
context new_ctx = extend(ctx, abst_name(b), abst_domain(b));
expr h_2 = new_state.m_menv->mk_metavar(new_ctx);
imitation = update_abstraction(b, h_1, h_2);
push_new_eq_constraint(new_state.m_queue, new_ctx, h_2, lift_free_vars(abst_body(b), i+1, 1), new_assumption);
push_new_eq_constraint(new_state.m_queue, new_ctx, h_2, lift_free_vars(abst_body(b), i+1, 1, new_state.m_menv), new_assumption);
} else {
imitation = lift_free_vars(b, i, 1);
imitation = lift_free_vars(b, i, 1, new_state.m_menv);
}
push_new_eq_constraint(new_state.m_queue, ctx_with_i, pop_meta_context(a), imitation, new_assumption);
new_cs->push_back(new_state, new_assumption);