feat(frontends/lean/elaborator): hide auxiliary 'match' hypothesis during elaboration
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6 changed files with 61 additions and 10 deletions
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@ -816,6 +816,10 @@ expr parse_local_equations(parser & p, expr const & fn) {
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return p.save_pos(mk_equations(fns.size(), eqns.size(), eqns.data()), pos);
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}
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static name * g_match_name = nullptr;
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bool is_match_binder_name(name const & n) { return n == *g_match_name; }
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/** \brief Use equations compiler infrastructure to implement match-with */
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expr parse_match(parser & p, unsigned, expr const *, pos_info const & pos) {
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buffer<expr> eqns;
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@ -823,7 +827,7 @@ expr parse_match(parser & p, unsigned, expr const *, pos_info const & pos) {
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try {
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t = p.parse_expr();
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p.check_token_next(get_with_tk(), "invalid 'match' expression, 'with' expected");
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expr fn = mk_local(p.mk_fresh_name(), "match", mk_expr_placeholder(), binder_info());
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expr fn = mk_local(p.mk_fresh_name(), *g_match_name, mk_expr_placeholder(), binder_info());
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if (p.curr_is_token(get_end_tk())) {
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p.next();
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// empty match-with
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@ -1466,4 +1470,11 @@ void register_decl_cmds(cmd_table & r) {
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add_cmd(r, cmd_info("abbreviation", "declare a new abbreviation", abbreviation_cmd));
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add_cmd(r, cmd_info("omit", "undo 'include' command", omit_cmd));
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}
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void initialize_decl_cmds() {
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g_match_name = new name(name::mk_internal_unique_name(), "match");
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}
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void finalize_decl_cmds() {
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delete g_match_name;
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}
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}
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@ -19,6 +19,9 @@ bool parse_univ_params(parser & p, buffer<name> & ps);
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expr parse_match(parser & p, unsigned, expr const *, pos_info const & pos);
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expr parse_local_equations(parser & p, expr const & fn);
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/** \brief Return true iff \c n is the auxiliary name used to elaborate match-expressions. */
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bool is_match_binder_name(name const & n);
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/** \brief Add universe levels from \c found_ls to \c ls_buffer (only the levels that do not already occur in \c ls_buffer are added).
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Then sort \c ls_buffer (using the order in which the universe levels were declared).
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*/
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@ -30,4 +33,7 @@ environment local_abbreviation_cmd(parser & p);
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/** \brief Parse a local attribute command */
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environment local_attribute_cmd(parser & p);
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void register_decl_cmds(cmd_table & r);
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void initialize_decl_cmds();
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void finalize_decl_cmds();
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}
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@ -52,6 +52,7 @@ Author: Leonardo de Moura
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#include "frontends/lean/begin_end_ext.h"
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#include "frontends/lean/elaborator_exception.h"
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#include "frontends/lean/calc.h"
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#include "frontends/lean/decl_cmds.h"
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namespace lean {
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/** \brief Custom converter that does not unfold constants that contains coercions from it.
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@ -828,9 +829,11 @@ expr elaborator::visit_binding(expr e, expr_kind k, constraint_seq & cs) {
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ds.push_back(d);
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expr l = mk_local(binding_name(e), d, binding_info(e));
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if (!is_match_binder_name(binding_name(e))) {
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if (binding_info(e).is_contextual())
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m_context.add_local(l);
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m_full_context.add_local(l);
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}
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ls.push_back(l);
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e = binding_body(e);
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}
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@ -1090,9 +1093,16 @@ static expr assign_equation_lhs_metas(type_checker & tc, expr const & eqns) {
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options o = fmt.get_options().update_if_undef(get_pp_implicit_name(), true);
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o = o.update_if_undef(get_pp_notation_option_name(), false);
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formatter new_fmt = fmt.update_options(o);
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format r("invalid recursive equation, left-hand-side contains meta-variable");
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expr const & f = get_app_fn(lhs);
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format r;
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if (is_local(f) && is_match_binder_name(local_pp_name(f))) {
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r = format("invalid 'match' expression, left-hand-side contains meta-variable");
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r += pp_indent_expr(new_fmt, app_arg(lhs));
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} else {
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r = format("invalid recursive equation, left-hand-side contains meta-variable");
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r += format(" (possible solution: provide implicit parameters occurring in left-hand-side explicitly)");
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r += pp_indent_expr(new_fmt, lhs);
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}
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return r;
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});
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}
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@ -1235,7 +1245,10 @@ expr elaborator::visit_equation(expr const & eq, constraint_seq & cs) {
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expr rhs_type = infer_type(new_rhs, cs);
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justification j = mk_justification(eq, [=](formatter const & fmt, substitution const & subst) {
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substitution s(subst);
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return pp_def_type_mismatch(fmt, local_pp_name(lhs_fn), s.instantiate(lhs_type), s.instantiate(rhs_type));
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name n = local_pp_name(lhs_fn);
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if (is_match_binder_name(n))
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n = "match";
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return pp_def_type_mismatch(fmt, n, s.instantiate(lhs_type), s.instantiate(rhs_type));
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});
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pair<expr, constraint_seq> new_rhs_cs = ensure_has_type(new_rhs, rhs_type, lhs_type, j);
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new_rhs = new_rhs_cs.first;
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@ -30,6 +30,7 @@ Author: Leonardo de Moura
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#include "frontends/lean/server.h"
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#include "frontends/lean/local_ref_info.h"
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#include "frontends/lean/obtain_expr.h"
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#include "frontends/lean/decl_cmds.h"
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namespace lean {
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void initialize_frontend_lean_module() {
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@ -59,8 +60,10 @@ void initialize_frontend_lean_module() {
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initialize_find_cmd();
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initialize_local_ref_info();
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initialize_obtain_expr();
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initialize_decl_cmds();
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}
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void finalize_frontend_lean_module() {
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finalize_decl_cmds();
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finalize_obtain_expr();
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finalize_local_ref_info();
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finalize_find_cmd();
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18
tests/lean/run/subst_test.lean
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18
tests/lean/run/subst_test.lean
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@ -0,0 +1,18 @@
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import data.nat
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open nat
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structure less_than (n : nat) := (val : nat) (lt : val < n)
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namespace less_than
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open decidable
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set_option pp.beta false
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definition less_than.has_decidable_eq [instance] (n : nat) : ∀ (i j : less_than n), decidable (i = j)
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| (mk ival ilt) (mk jval jlt) :=
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match nat.has_decidable_eq ival jval with
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| inl veq := inl (by subst veq)
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| inr vne := inr (by intro h; injection h; contradiction)
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end
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end less_than
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@ -1,2 +1,2 @@
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unzip_error.lean:9:2: error: invalid recursive equation, left-hand-side contains meta-variable (possible solution: provide implicit parameters occurring in left-hand-side explicitly)
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match (@mk (vector A ?M_1) (vector B ?M_1) va vb)
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unzip_error.lean:9:2: error: invalid 'match' expression, left-hand-side contains meta-variable
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@mk (vector A ?M_1) (vector B ?M_1) va vb
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