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lean4-htt/src/frontends/lean/builtin_exprs.cpp
Leonardo de Moura 7cdf917c97 fix: compiler do a; b as a >>= fun _ => b 
Consider the following example
```lean
def div!: Nat → Nat → Nat
| x, 0 => panic! "division by zero"
| x, y => x/y

def weird (x : Nat) : MetaM Nat :=
unless (x > 0) (throwOther "x == 0") *>
let y := div! 10 x;
pure y
```
If we execute `weird 0`, it produces a "division by zero" panic
message.
This is a simple version of a much bigger function in the new
frontend.
This is not due to a bug in the compiler.
It produces the panic message because of the `do`-encoding
refactoring. Recall that, a few months ago,
we started to compile `do a; b` as `a *> b` (i.e., `seqRight a b`).
Thus, the example above is
`seqRight action1 (let y := div! 10 x; pure y)`
where `action1` is the `unless ...`.
In A-normal form, this is equivalent to

```lean
let y:= div! 10 x;
let action2 := pure y;
seqRight action1 action2
```
Thus, we execute `div! 10 x` before we even execute the `seqRight`.
This is counterintuitive and demonstrates once again how impure
features such as `panic!` are dangerous.

This commit reverts the `do`-encoding refactoring, and encodes
`do a; b` as `a >>= fun _ b` as we did in Lean3.

cc @Kha
2020-08-15 15:51:00 -07:00

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/*
Copyright (c) 2014 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Leonardo de Moura
*/
#include <string>
#include <algorithm>
#include "library/export_decl.h"
#include <lean/sstream.h>
#include "util/option_declarations.h"
#include "kernel/abstract.h"
#include "kernel/instantiate.h"
#include "library/annotation.h"
#include "library/placeholder.h"
#include "library/explicit.h"
#include "library/aliases.h"
#include "library/constants.h"
#include "library/string.h"
#include "library/trace.h"
#include "library/compiler/borrowed_annotation.h"
#include "library/equations_compiler/equations.h"
#include "frontends/lean/builtin_exprs.h"
#include "frontends/lean/decl_cmds.h"
#include "frontends/lean/decl_util.h"
#include "frontends/lean/token_table.h"
#include "frontends/lean/parser.h"
#include "frontends/lean/util.h"
#include "frontends/lean/prenum.h"
#include "frontends/lean/tokens.h"
#include "frontends/lean/match_expr.h"
#include "frontends/lean/brackets.h"
#include "frontends/lean/elaborator.h"
#include "frontends/lean/typed_expr.h"
#include "frontends/lean/choice.h"
#ifndef LEAN_DEFAULT_PARSER_CHECKPOINT_HAVE
#define LEAN_DEFAULT_PARSER_CHECKPOINT_HAVE true
#endif
namespace lean {
static name * g_parser_checkpoint_have = nullptr;
bool get_parser_checkpoint_have(options const & opts) {
return opts.get_bool(*g_parser_checkpoint_have, LEAN_DEFAULT_PARSER_CHECKPOINT_HAVE);
}
using namespace notation; // NOLINT
static name * g_no_universe_annotation = nullptr;
bool is_sort_wo_universe(expr const & e) {
return is_annotation(e, *g_no_universe_annotation);
}
expr mk_sort_wo_universe(parser & p, pos_info const & pos, bool is_type) {
expr r = p.save_pos(mk_sort(is_type ? mk_level_one() : mk_level_zero()), pos);
return p.save_pos(mk_annotation(*g_no_universe_annotation, r), pos);
}
static expr parse_Type(parser & p, unsigned, expr const *, pos_info const & pos) {
if (p.curr_is_token(get_llevel_curly_tk())) {
p.next();
level l = mk_succ(p.parse_level());
p.check_token_next(get_rcurly_tk(), "invalid Type expression, '}' expected");
return p.save_pos(mk_sort(l), pos);
} else {
return mk_sort_wo_universe(p, pos, true);
}
}
static expr parse_Sort(parser & p, unsigned, expr const *, pos_info const & pos) {
if (p.curr_is_token(get_llevel_curly_tk())) {
p.next();
level l = p.parse_level();
p.check_token_next(get_rcurly_tk(), "invalid Sort expression, '}' expected");
return p.save_pos(mk_sort(l), pos);
} else {
return mk_sort_wo_universe(p, pos, false);
}
}
static expr parse_Type_star(parser & p, unsigned, expr const *, pos_info const & pos) {
return p.save_pos(mk_sort(mk_succ(mk_level_placeholder())), pos);
}
static expr parse_Sort_star(parser & p, unsigned, expr const *, pos_info const & pos) {
return p.save_pos(mk_sort(mk_level_placeholder()), pos);
}
static name * g_let_match_name = nullptr;
static expr parse_let(parser & p, pos_info const & pos, bool in_do_block);
static expr parse_do(parser & p, bool has_braces);
static expr parse_let_body(parser & p, pos_info const & pos, bool in_do_block) {
if (in_do_block) {
{
if (p.curr_is_token(get_semicolon_tk())) {
p.next();
} else {
p.check_token_next(get_semicolon_tk(), "invalid 'do' block 'let' declaration, ';' expected");
}
if (p.curr_is_token(get_let_tk())) {
p.next();
return parse_let(p, pos, in_do_block);
} else {
return parse_do(p, false);
}
}
} else {
if (p.curr_is_token(get_semicolon_tk())) {
p.next();
return p.parse_expr();
} else {
p.maybe_throw_error({"invalid let declaration, ';' expected", p.pos()});
return p.parse_expr();
}
}
}
// Distribute mk_typed_expr over choice expression.
// see issue #768
static expr mk_typed_expr_distrib_choice(parser & p, expr const & type, expr const & value, pos_info const & pos) {
if (is_choice(value)) {
buffer<expr> new_choices;
for (unsigned i = 0; i < get_num_choices(value); i++) {
new_choices.push_back(mk_typed_expr_distrib_choice(p, type, get_choice(value, i), pos));
}
return p.save_pos(mk_choice(new_choices.size(), new_choices.data()), pos);
} else {
return p.save_pos(mk_typed_expr(type, value), pos);
}
}
static expr parse_let(parser & p, pos_info const & pos, bool in_do_block) {
parser::local_scope scope1(p);
if (!in_do_block && p.parse_local_notation_decl()) {
return parse_let_body(p, pos, in_do_block);
} else if (p.curr_is_identifier()) {
auto id_pos = p.pos();
name id = p.check_atomic_id_next("invalid let declaration, atomic identifier expected");
expr type;
expr value;
if (p.curr_is_token(get_assign_tk())) {
p.next();
type = p.save_pos(mk_expr_placeholder(), id_pos);
value = p.parse_expr();
} else if (p.curr_is_token(get_colon_tk())) {
p.next();
type = p.parse_expr();
p.check_token_next(get_assign_tk(), "invalid declaration, ':=' expected");
value = p.parse_expr();
} else {
parser::local_scope scope2(p);
buffer<expr> ps;
unsigned rbp = 0;
auto lenv = p.parse_binders(ps, rbp);
if (p.curr_is_token(get_colon_tk())) {
p.next();
type = p.parse_scoped_expr(ps, lenv);
type = Pi(ps, type, p);
} else {
type = p.save_pos(mk_expr_placeholder(), id_pos);
}
p.check_token_next(get_assign_tk(), "invalid let declaration, ':=' expected");
value = p.parse_scoped_expr(ps, lenv);
value = Fun(ps, value, p);
}
expr x = mk_local(id, type);
p.add_local_expr(id, p.save_pos(x, id_pos));
expr b = parse_let_body(p, pos, in_do_block);
return p.save_pos(mk_let(id, type, value, abstract(b, x)), pos);
} else {
buffer<expr> new_locals;
expr lhs = p.parse_pattern(new_locals);
expr type;
if (p.curr_is_token(get_colon_tk())) {
p.next();
type = mk_pi("a", p.parse_expr(), mk_expr_placeholder());
} else {
type = mk_expr_placeholder();
}
p.check_token_next(get_assign_tk(), "invalid let declaration, ':=' expected");
expr value = p.parse_expr();
for (expr const & l : new_locals)
p.add_local(l);
expr body = parse_let_body(p, pos, in_do_block);
match_definition_scope match_scope(p.env());
expr fn = p.save_pos(mk_local(p.next_name(), *g_let_match_name, type, mk_rec_info()), pos);
expr eqn = Fun(fn, Fun(new_locals, p.save_pos(mk_equation(p.rec_save_pos(mk_app(fn, lhs), pos), body), pos), p), p);
equations_header h = mk_match_header(match_scope.get_name(), match_scope.get_actual_name());
expr eqns = p.save_pos(mk_equations(h, 1, &eqn), pos);
expr e = mk_app(eqns, value);
return p.save_pos(e, pos);
}
}
static expr parse_let_expr(parser & p, unsigned, expr const *, pos_info const & pos) {
bool in_do_block = false;
return parse_let(p, pos, in_do_block);
}
static name * g_do_match_name = nullptr;
static std::tuple<optional<expr>, expr, expr, optional<expr>> parse_do_action(parser & p, buffer<expr> & new_locals) {
auto lhs_pos = p.pos();
optional<expr> lhs = some(p.parse_pattern_or_expr());
expr type, curr;
optional<expr> else_case;
if (p.curr_is_token(get_colon_tk())) {
p.next();
type = p.parse_expr();
if (is_placeholder(unwrap_pos(*lhs))) {
lhs = mk_local("_x", type);
}
if (!is_local(unwrap_pos(*lhs))) {
p.maybe_throw_error({"invalid 'do' block, unexpected ':' the left hand side is a pattern", lhs_pos});
lhs = mk_local("_x", type);
}
lhs = p.save_pos(mk_local(local_pp_name_p(*lhs), type), lhs_pos);
new_locals.clear();
new_locals.push_back(*lhs);
p.check_token_next(get_larrow_tk(), "invalid 'do' block, '←' expected");
curr = p.parse_expr();
} else if (p.curr_is_token(get_larrow_tk())) {
p.next();
type = p.save_pos(mk_expr_placeholder(), lhs_pos);
bool skip_main_fn = false;
lhs = p.patexpr_to_pattern(*lhs, skip_main_fn, new_locals);
curr = p.parse_expr();
if (p.curr_is_token(get_bar_tk())) {
p.next();
else_case = p.parse_expr();
}
} else {
curr = p.patexpr_to_expr(*lhs);
type = p.save_pos(mk_expr_placeholder(), lhs_pos);
lhs = none_expr();
}
return std::make_tuple(lhs, type, curr, else_case);
}
static expr mk_bind_fn(parser & p) {
return mk_no_info(p.id_to_expr("bind", pos_info {}, /* resolve_only */ true));
}
static name * g_do_failure_eq = nullptr;
/* Mark for automatic failure equation when pattern matching in do-expressions. */
expr mark_do_failure_eq(expr const & e) {
return mk_annotation(*g_do_failure_eq, e);
}
bool is_do_failure_eq(expr const & e) {
auto it = e;
while (is_lambda(it))
it = binding_body(it);
if (!is_equation(it)) return false;
return is_annotation(equation_rhs(it), *g_do_failure_eq);
}
static expr parse_do(parser & p, bool has_braces) {
parser::local_scope scope(p);
buffer<expr> es;
buffer<pos_info> ps;
buffer<optional<expr>> lhss;
buffer<optional<expr>> else_cases;
buffer<list<expr>> lhss_locals;
while (true) {
if (p.curr_is_token(get_let_tk())) {
auto pos = p.pos();
p.next();
bool in_do_block = true;
es.push_back(parse_let(p, pos, in_do_block));
break;
} else {
auto lhs_pos = p.pos();
ps.push_back(lhs_pos);
buffer<expr> new_locals;
optional<expr> lhs, else_case;
expr type, curr;
std::tie(lhs, type, curr, else_case) = parse_do_action(p, new_locals);
es.push_back(curr);
if (/* p.curr_is_token(get_comma_tk()) || */ p.curr_is_token(get_semicolon_tk())) {
p.next();
for (expr const & l : new_locals)
p.add_local(l);
if (lhs && !is_local(*lhs)) {
// if lhs is a pattern, we need to save the locals to create the match
lhss_locals.push_back(to_list(new_locals));
} else {
lhss_locals.push_back(list<expr>());
}
lhss.push_back(lhs);
else_cases.push_back(else_case);
} else {
if (lhs) {
p.maybe_throw_error({"the last statement in a 'do' block must be an expression", lhs_pos});
}
break;
}
}
}
if (has_braces) {
p.check_token_next(get_rcurly_tk(), "invalid 'do' block, '}' expected");
}
lean_assert(!es.empty());
lean_assert(es.size() == lhss.size() + 1);
if (es.size() == 1)
return es[0];
unsigned i = es.size();
--i;
expr r = es[i];
while (i > 0) {
--i;
if (auto lhs = lhss[i]) {
if (is_local_p(*lhs)) {
r = p.rec_save_pos(mk_app(p.save_pos(mk_bind_fn(p), ps[i]), es[i], Fun(*lhs, r, p)), ps[i]);
} else {
// must introduce a "fake" match
auto pos = ps[i];
match_definition_scope match_scope(p.env());
expr fn = p.save_pos(mk_local(p.next_name(), *g_do_match_name, mk_expr_placeholder(), mk_rec_info()), pos);
buffer<expr> locals;
to_buffer(lhss_locals[i], locals);
buffer<expr> eqs;
eqs.push_back(Fun(fn, Fun(locals, p.save_pos(mk_equation(p.rec_save_pos(mk_app(fn, *lhs), pos), r), pos), p), p));
expr else_case;
bool ignore_if_unused;
if (optional<expr> r = else_cases[i]) {
else_case = *r;
ignore_if_unused = false;
expr x = mk_local(p.next_name(), "_x", mk_expr_placeholder(), mk_binder_info());
expr else_eq = Fun(fn, Fun(x, p.save_pos(mk_equation(p.rec_save_pos(mk_app(fn, x), pos),
else_case,
ignore_if_unused),
pos), p), p);
eqs.push_back(else_eq);
}
equations_header h = mk_match_header(match_scope.get_name(), match_scope.get_actual_name());
expr eqns = p.save_pos(mk_equations(h, eqs.size(), eqs.data()), pos);
expr local = mk_local("_p", mk_expr_placeholder());
expr match = p.mk_app(eqns, local, pos);
r = p.rec_save_pos(mk_app(p.save_pos(mk_bind_fn(p), ps[i]),
es[i],
p.save_pos(Fun(local, match, p), pos)),
pos);
}
} else {
expr action2 = p.save_pos(mk_lambda("_", mk_expr_placeholder(), r), ps[i]);
r = p.rec_save_pos(mk_app(p.save_pos(mk_bind_fn(p), ps[i]), es[i], action2), ps[i]);
// r = p.rec_save_pos(mk_app(p.save_pos(mk_const({"HasSeqRight", "seqRight"}), ps[i]), es[i], r), ps[i]);
}
}
return r;
}
static expr parse_do_expr(parser & p, unsigned, expr const *, pos_info const &) {
bool has_braces = false;
if (p.curr_is_token(get_lcurly_tk())) {
has_braces = true;
p.next();
}
return parse_do(p, has_braces);
}
static expr parse_unit(parser & p, unsigned, expr const *, pos_info const & pos) {
return p.save_pos(mk_constant(get_unit_unit_name()), pos);
}
static expr parse_proof(parser & p);
static expr parse_proof(parser & p) {
if (p.curr_is_token(get_from_tk())) {
// parse: 'from' expr
p.next();
return p.parse_expr();
} else {
return p.parser_error_or_expr({"invalid expression, 'from' expected", p.pos()});
}
}
static expr parse_have(parser & p, unsigned, expr const *, pos_info const & pos) {
auto id_pos = p.pos();
name id;
expr prop;
if (p.curr_is_identifier()) {
id = p.get_name_val();
p.next();
if (p.curr_is_token(get_colon_tk())) {
p.next();
prop = p.parse_expr();
} else {
expr left = p.id_to_expr(id, id_pos);
id = get_this_tk();
unsigned rbp = 0;
while (rbp < p.curr_lbp()) {
left = p.parse_led(left);
}
prop = left;
}
} else {
id = get_this_tk();
prop = p.parse_expr();
}
expr proof;
if (p.curr_is_token(get_assign_tk())) {
p.next();
proof = p.parse_expr();
} else {
proof = parse_proof(p);
}
p.check_token_next(get_semicolon_tk(), "invalid 'have' declaration, ';' expected");
parser::local_scope scope(p);
expr l = p.save_pos(mk_local(id, prop), pos);
p.add_local(l);
expr body = p.parse_expr();
body = abstract(body, unwrap_pos(l));
if (get_parser_checkpoint_have(p.get_options()))
body = mk_checkpoint_annotation(body);
expr r = p.save_pos(mk_have_annotation(p.save_pos(mk_lambda(id, prop, body), pos)), pos);
return p.mk_app(r, proof, pos);
}
static expr parse_show(parser & p, unsigned, expr const *, pos_info const & pos) {
expr prop = p.parse_expr();
expr proof = parse_proof(p);
expr b = p.save_pos(mk_lambda(get_this_tk(), prop, mk_bvar(0)), pos);
expr r = p.mk_app(b, proof, pos);
return p.save_pos(mk_show_annotation(r), pos);
}
static expr parse_suffices(parser & p, unsigned, expr const *, pos_info const & pos) {
auto prop_pos = p.pos();
name id;
expr from;
if (p.curr_is_identifier()) {
id = p.get_name_val();
p.next();
if (p.curr_is_token(get_colon_tk())) {
p.next();
from = p.parse_expr();
} else {
expr left = p.id_to_expr(id, prop_pos);
id = get_this_tk();
unsigned rbp = 0;
while (rbp < p.curr_lbp()) {
left = p.parse_led(left);
}
from = left;
}
} else {
id = get_this_tk();
from = p.parse_expr();
}
expr local = p.save_pos(mk_local(id, from), prop_pos);
expr body;
{
parser::local_scope scope(p);
p.add_local(local);
body = parse_proof(p);
}
expr proof = p.save_pos(Fun(local, body, p), pos);
p.check_token_next(get_semicolon_tk(), "invalid 'suffices' declaration, ';' expected");
expr rest = p.parse_expr();
expr r = p.mk_app(proof, rest, pos);
return p.save_pos(mk_suffices_annotation(r), pos);
}
static expr * g_not = nullptr;
static unsigned g_then_else_prec = 0;
static expr parse_ite(parser & p, expr const & c, pos_info const & pos) {
if (!p.env().find(get_ite_name()))
throw parser_error("invalid use of 'if-then-else' expression, environment does not contain 'ite' definition", pos);
p.check_token_next(get_then_tk(), "invalid 'if-then-else' expression, 'then' expected");
expr t = p.parse_expr(g_then_else_prec);
p.check_token_next(get_else_tk(), "invalid 'if-then-else' expression, 'else' expected");
expr e = p.parse_expr(g_then_else_prec);
return p.save_pos(mk_app(mk_constant(get_ite_name()), c, t, e), pos);
}
static expr parse_dite(parser & p, name const & H_name, expr const & c, pos_info const & pos) {
p.check_token_next(get_then_tk(), "invalid 'if-then-else' expression, 'then' expected");
expr t, e;
{
parser::local_scope scope(p);
expr H = mk_local(H_name, c);
p.add_local(H);
auto pos = p.pos();
t = p.save_pos(Fun(H, p.parse_expr(g_then_else_prec), p), pos);
}
p.check_token_next(get_else_tk(), "invalid 'if-then-else' expression, 'else' expected");
{
parser::local_scope scope(p);
expr H = mk_local(H_name, mk_app(*g_not, c));
p.add_local(H);
auto pos = p.pos();
e = p.save_pos(Fun(H, p.parse_expr(g_then_else_prec), p), pos);
}
return p.save_pos(mk_app(p.save_pos(mk_constant(get_dite_name()), pos), c, t, e), pos);
}
static expr parse_if_then_else(parser & p, unsigned, expr const *, pos_info const & pos) {
pair<optional<name>, expr> ie = p.parse_qualified_expr();
if (ie.first)
return parse_dite(p, *ie.first, ie.second, pos);
else
return parse_ite(p, ie.second, pos);
}
static expr parse_explicit_core(parser & p, pos_info const & pos, bool partial) {
if (!p.curr_is_identifier())
return p.parser_error_or_expr({sstream() << "invalid '" << (partial ? "@@" : "@") << "', identifier expected", p.pos()});
expr fn = unwrap_pos(p.parse_id());
if (is_choice(fn)) {
sstream s;
s << "invalid '" << (partial ? "@@" : "@") << "', function is overloaded, use fully qualified names (overloads: ";
for (unsigned i = 0; i < get_num_choices(fn); i++) {
if (i > 0) s << ", ";
expr const & c = get_choice(fn, i);
if (is_constant(c))
s << const_name(c);
else if (is_local(c))
s << local_pp_name(c);
else
s << "[other]";
}
s << ")";
return p.parser_error_or_expr({s, pos});
} else if (!is_as_atomic(fn) && !is_constant(fn) && !is_local(fn)) {
return p.parser_error_or_expr({sstream() << "invalid '" << (partial ? "@@" : "@") << "', function must be a constant or variable", pos});
}
if (partial)
return p.save_pos(mk_partial_explicit(fn), pos);
else
return p.save_pos(mk_explicit(fn), pos);
}
static expr parse_explicit_expr(parser & p, unsigned, expr const *, pos_info const & pos) {
return parse_explicit_core(p, pos, false);
}
static expr parse_partial_explicit_expr(parser & p, unsigned, expr const *, pos_info const & pos) {
return parse_explicit_core(p, pos, true);
}
static expr parse_sorry(parser & p, unsigned, expr const *, pos_info const & pos) {
return p.mk_sorry(pos);
}
static expr parse_borrowed_expr(parser & p, unsigned, expr const *, pos_info const & pos) {
expr e = p.parse_expr(get_max_prec()-1);
return p.save_pos(mk_borrowed(e), pos);
}
// We have disabled the SMT frontend
// static expr parse_pattern(parser & p, unsigned, expr const * args, pos_info const & pos) {
// return p.save_pos(mk_pattern_hint(args[0]), pos);
// }
static expr parse_quoted_name(parser & p, unsigned, expr const *, pos_info const & pos) {
bool resolve = false;
name id;
if (p.curr_is_token(get_placeholder_tk())) {
p.next();
id = "_";
} else {
if (p.curr_is_token(get_backtick_tk())) {
p.next();
resolve = true;
}
if (p.curr_is_keyword() || p.curr_is_command()) {
if (resolve)
return p.parser_error_or_expr({"invalid resolved quote symbol, identifier is a keyword/command", pos});
id = p.get_token_info().token();
p.next();
} else {
id = p.check_id_next("invalid quoted name, identifier expected");
}
}
if (resolve) {
parser::error_if_undef_scope scope(p);
bool resolve_only = true;
expr e = p.id_to_expr(id, pos, resolve_only);
if (is_constant(e)) {
id = const_name(e);
} else if (is_local(e)) {
id = local_pp_name(e);
} else if (is_choice(e)) {
sstream ss;
ss << "invalid resolved quoted symbol, it is ambiguous, possible interpretations:";
for (unsigned i = 0; i < get_num_choices(e); i++)
ss << " " << get_choice(e, i);
ss << " (solution: use fully qualified names)";
return p.parser_error_or_expr({ss, pos});
} else {
return p.parser_error_or_expr({"invalid quoted symbol, failed to resolve it "
"(solution: use `<identifier> to bypass name resolution)", pos});
}
}
lean_assert(id.is_string());
expr e = quote(id);
return p.rec_save_pos(e, pos);
}
static name * g_anonymous_constructor = nullptr;
expr mk_anonymous_constructor(expr const & e) { return mk_annotation(*g_anonymous_constructor, e); }
bool is_anonymous_constructor(expr const & e) { return is_annotation(e, *g_anonymous_constructor); }
expr const & get_anonymous_constructor_arg(expr const & e) {
lean_assert(is_anonymous_constructor(e));
return get_annotation_arg(e);
}
static expr parse_constructor_core(parser & p, pos_info const & pos) {
buffer<expr> args;
while (!p.curr_is_token(get_rangle_tk())) {
args.push_back(p.parse_expr());
if (p.curr_is_token(get_comma_tk())) {
p.next();
} else {
break;
}
}
p.check_token_next(get_rangle_tk(), "invalid constructor, `⟩` expected");
expr fn = p.save_pos(mk_expr_placeholder(), pos);
return p.save_pos(mk_anonymous_constructor(mk_app(fn, args)), pos);
}
static expr parse_constructor(parser & p, unsigned, expr const *, pos_info const & pos) {
return parse_constructor_core(p, pos);
}
static expr parse_lambda_core(parser & p, pos_info const & pos);
static expr parse_lambda_binder(parser & p, pos_info const & pos) {
parser::local_scope scope1(p);
buffer<expr> locals;
auto new_env = p.parse_binders(locals, 0);
for (expr const & local : locals)
p.add_local(local);
parser::local_scope scope2(p, new_env);
expr body;
if (/* p.curr_is_token(get_comma_tk()) || */ p.curr_is_token(get_darrow_tk())) {
p.next();
body = p.parse_expr();
} else if (p.curr_is_token(get_langle_tk())) {
body = parse_lambda_core(p, pos);
} else {
p.maybe_throw_error({"invalid lambda expression, '=>' or '⟨' expected", p.pos()});
body = p.parse_expr();
}
return p.rec_save_pos(Fun(locals, body, p), pos);
}
static name * g_lambda_match_name = nullptr;
static expr parse_lambda_constructor(parser & p, pos_info const & ini_pos) {
lean_assert(p.curr_is_token(get_langle_tk()));
parser::local_scope scope(p);
auto pos = p.pos();
p.next();
buffer<expr> locals;
expr pattern = p.parse_pattern([&](parser & p) { return parse_constructor_core(p, pos); }, locals);
for (expr const & local : locals)
p.add_local(local);
expr body;
if (p.curr_is_token(get_darrow_tk())) {
p.next();
body = p.parse_expr();
} else {
body = parse_lambda_core(p, ini_pos);
}
match_definition_scope match_scope(p.env());
expr fn = p.save_pos(mk_local(p.next_name(), *g_lambda_match_name, mk_expr_placeholder(), mk_rec_info()), pos);
expr eqn = Fun(fn, Fun(locals, p.save_pos(mk_equation(p.rec_save_pos(mk_app(fn, pattern), pos), body), pos), p), p);
equations_header h = mk_match_header(match_scope.get_name(), match_scope.get_actual_name());
expr x = p.rec_save_pos(mk_local(p.next_name(), "_x", mk_expr_placeholder(), mk_binder_info()), pos);
return p.rec_save_pos(Fun(x, mk_app(mk_equations(h, 1, &eqn), x)), pos);
}
static expr parse_lambda_core(parser & p, pos_info const & pos) {
if (p.curr_is_token(get_langle_tk())) {
return parse_lambda_constructor(p, pos);
} else {
return parse_lambda_binder(p, pos);
}
}
static expr parse_lambda(parser & p, unsigned, expr const *, pos_info const & pos) {
return parse_lambda_core(p, pos);
}
static expr parse_list(parser & p, unsigned, expr const *, pos_info const & pos) {
buffer<expr> elems;
if (!p.curr_is_token(get_rbracket_tk())) {
while (true) {
expr elem = p.parse_expr();
elems.push_back(elem);
if (!p.curr_is_token(get_comma_tk()))
break;
p.next();
}
}
p.check_token_next(get_rbracket_tk(), "invalid list, ']' expected");
expr r = p.save_pos(mk_constant(get_list_nil_name()), pos);
unsigned i = elems.size();
while (i > 0) {
--i;
expr elem = elems[i];
r = p.save_pos(mk_app(mk_constant(get_list_cons_name()), elem, r), p.pos_of(elem));
}
return r;
}
static expr parse_array(parser & p, unsigned n, expr const * l, pos_info const & pos) {
expr xs = parse_list(p, n, l, pos);
return p.save_pos(mk_app(mk_constant(get_list_to_array_name()), xs), pos);
}
static void consume_rparen(parser & p) {
p.check_token_next(get_rparen_tk(), "invalid expression, `)` expected");
}
static name * g_infix_function = nullptr;
bool is_infix_function(expr const & e) {
return is_annotation(e, *g_infix_function);
}
expr mk_infix_function(expr const & e) {
return mk_annotation(*g_infix_function, e);
}
static expr parse_lparen(parser & p, unsigned, expr const *, pos_info const & pos) {
expr e = p.parse_expr();
if (p.curr_is_token(get_comma_tk())) {
buffer<expr> args;
args.push_back(e);
while (p.curr_is_token(get_comma_tk())) {
p.next();
args.push_back(p.parse_expr());
}
consume_rparen(p);
expr r = args.back();
unsigned i = args.size() - 1;
while (i > 0) {
--i;
r = p.save_pos(mk_app(p.save_pos(mk_constant(get_prod_mk_name()), pos),
args[i], r), pos);
}
return r;
} else if (p.curr_is_token(get_colon_tk())) {
p.next();
expr t = p.parse_expr();
consume_rparen(p);
return mk_typed_expr_distrib_choice(p, t, e, pos);
} else {
consume_rparen(p);
return e;
}
}
static expr parse_inaccessible(parser & p, unsigned, expr const *, pos_info const & pos) {
expr e = p.parse_expr();
if (!p.in_pattern()) {
p.maybe_throw_error({"inaccesible pattern notation `.(t)` can only be used in patterns", pos});
return e;
}
p.check_token_next(get_rparen_tk(), "invalid inaccesible pattern, `)` expected");
return p.save_pos(mk_inaccessible(e), pos);
}
static expr parse_atomic_inaccessible(parser & p, unsigned, expr const *, pos_info const & pos) {
if (!p.in_pattern()) {
return p.parser_error_or_expr({"inaccesible pattern notation `._` can only be used in patterns", pos});
}
return p.save_pos(mk_inaccessible(p.save_pos(mk_expr_placeholder(), pos)), pos);
}
expr mk_annotation_with_pos(parser &, name const & a, expr const & e, pos_info const & pos) {
expr r = mk_annotation(a, e);
return save_pos(r, pos);
}
static expr parse_parser(parser & p, bool leading, pos_info const & pos) {
name kind = get_curr_declaration_name();
expr prec = save_pos(mk_prenum(mpz(get_max_prec())), pos);
if (p.curr_is_token(get_colon_tk())) {
p.next();
prec = p.parse_expr(get_max_prec());
}
expr e = p.parse_expr();
name n = leading ? get_lean_parser_leading_node_name() : get_lean_parser_trailing_node_name();
expr r = mk_app(mk_constant(n), quote(kind), prec, e);
if (leading && kind.is_string()) {
r = mk_app(mk_constant({"Lean", "Parser", "withAntiquot"}),
mk_app(mk_constant({"Lean", "Parser", "mkAntiquot"}),
quote(kind.get_string().data()),
quote(kind)),
r);
}
return save_pos(r, pos);
}
static expr parse_lparser(parser & p, unsigned, expr const *, pos_info const & pos) {
return parse_parser(p, true, pos);
}
static expr parse_tparser(parser & p, unsigned, expr const *, pos_info const & pos) {
return parse_parser(p, false, pos);
}
static expr parse_panic(parser & p, unsigned, expr const *, pos_info const & pos) {
expr e = p.parse_expr();
std::string mod = p.env().get_main_module().to_string();
expr r = mk_app(mk_constant(get_panic_with_pos_name()), quote(mod.c_str()), quote(pos.first), quote(pos.second), e);
return save_pos(r, pos);
}
static expr parse_trace(parser & p, unsigned, expr const *, pos_info const & pos) {
expr k = p.parse_expr(get_max_prec());
expr e = p.parse_expr(get_max_prec());
expr m = mk_constant(get_lean_message_data_name());
e = mk_typed_expr(m, e);
expr r = mk_app(mk_constant(get_lean_monad_tracer_trace_name()), k, mk_lambda("_", mk_unit(), e, binder_info()));
return save_pos(r, pos);
}
template<class T>
static T handle_res(object * r, parser const & p) {
if (cnstr_tag(r) == 0) {
throw parser_error(sstream() << cnstr_get_ref_t<string_ref>(object_ref(r), 0).to_std_string(), p.pos());
} else {
return cnstr_get_ref_t<T>(object_ref(r), 0);
}
}
extern "C" object * lean_parse_expr(object * env, object * input, object * pos);
static object_ref parse_expr(parser & p) {
object_ref tup = handle_res<object_ref>(lean_parse_expr(p.env().to_obj_arg(), mk_string(p.m_scanner.m_curr_line), nat(p.m_scanner.m_tk_spos).to_obj_arg()), p);
size_t col = cnstr_get_ref_t<nat>(tup, 1).get_small_value();
col = std::min(col, p.m_scanner.m_curr_line.size() - 1);
p.m_scanner.skip_to_pos(pos_info {0, col});
p.next();
return cnstr_get_ref(tup, 0);
}
static object * mk_lean_ctx(parser & p) {
buffer<name> locals;
for (auto const & l : p.get_local_expr_decls().get_entries())
locals.push_back(l.first);
buffer<name> open_nss;
for (auto const & e : get_active_export_decls(p.env()))
open_nss.push_back(e.m_ns);
return mk_cnstr(0,
p.env().to_obj_arg(),
to_list_ref(locals).to_obj_arg(),
to_list_ref(open_nss).to_obj_arg()).steal();
}
extern "C" object * lean_expand_stx_quot(object * ctx, object * stx);
static expr parse_stx_quot(parser & p, unsigned, expr const *, pos_info const & /* pos */) {
object_ref stx = parse_expr(p);
return handle_res<expr>(lean_expand_stx_quot(mk_lean_ctx(p), stx.steal()), p);
}
extern "C" object * lean_expand_match_syntax(object * ctx, object * discr, object * alts);
extern "C" object * lean_get_antiquot_vars(object * ctx, object * pats);
static expr parse_match_syntax(parser & p, unsigned, expr const *, pos_info const & /* pos */) {
parser::local_scope scope1(p);
parser::error_if_undef_scope eius(p);
expr discr = p.parse_expr();
p.check_token_next(get_with_tk(), "invalid 'match_syntax' expression, 'with' expected");
unsigned case_column = p.pos().second;
if (is_eqn_prefix(p))
p.next(); // optional '|' in the first case
buffer<object_ref> alts;
while (true) {
buffer<object_ref> lhs_args;
lhs_args.push_back(parse_expr(p));
while (p.curr_is_token(get_comma_tk())) {
p.next();
lhs_args.push_back(parse_expr(p));
}
list_ref<object_ref> lhs(lhs_args);
p.check_token_next(get_darrow_tk(), "invalid 'match_syntax' expression, '=>' expected");
{
parser::local_scope scope2(p);
auto vars = handle_res<list_ref<name>>(lean_get_antiquot_vars(mk_lean_ctx(p), lhs.to_obj_arg()), p);
for (name const & var : vars)
p.add_local_expr(var, mk_fvar(var));
expr rhs = p.parse_expr();
alts.push_back(mk_cnstr(0, lhs.to_obj_arg(), rhs.to_obj_arg()));
}
// terminate match on dedent
if (!is_eqn_prefix(p) || p.pos().second < case_column)
break;
p.next();
}
return handle_res<expr>(lean_expand_match_syntax(mk_lean_ctx(p), discr.to_obj_arg(), list_ref<object_ref>(alts).to_obj_arg()), p);
}
parse_table init_nud_table() {
action Expr(mk_expr_action());
action Skip(mk_skip_action());
action Binders(mk_binders_action());
expr x0 = mk_bvar(0);
parse_table r;
r = r.add({transition("have", mk_ext_action(parse_have))}, x0);
r = r.add({transition("show", mk_ext_action(parse_show))}, x0);
r = r.add({transition("suffices", mk_ext_action(parse_suffices))}, x0);
r = r.add({transition("if", mk_ext_action(parse_if_then_else))}, x0);
r = r.add({transition("(", mk_ext_action(parse_lparen))}, x0);
r = r.add({transition("[", mk_ext_action(parse_list))}, x0);
r = r.add({transition("#[", mk_ext_action(parse_array))}, x0);
r = r.add({transition("⟨", mk_ext_action(parse_constructor))}, x0);
r = r.add({transition("{", mk_ext_action(parse_curly_bracket))}, x0);
r = r.add({transition(".(", mk_ext_action(parse_inaccessible))}, x0);
r = r.add({transition("._", mk_ext_action(parse_atomic_inaccessible))}, x0);
r = r.add({transition("`", mk_ext_action(parse_quoted_name))}, x0);
// r = r.add({transition("(:", Expr), transition(":)", mk_ext_action(parse_pattern))}, x0);
r = r.add({transition("()", mk_ext_action(parse_unit))}, x0);
r = r.add({transition("fun", mk_ext_action(parse_lambda))}, x0);
r = r.add({transition("forall", Binders), transition(",", mk_scoped_expr_action(x0, 0, false))}, x0);
r = r.add({transition("Type", mk_ext_action(parse_Type))}, x0);
r = r.add({transition("Type*", mk_ext_action(parse_Type_star))}, x0);
r = r.add({transition("Sort", mk_ext_action(parse_Sort))}, x0);
r = r.add({transition("Sort*", mk_ext_action(parse_Sort_star))}, x0);
r = r.add({transition("let", mk_ext_action(parse_let_expr))}, x0);
r = r.add({transition("@", mk_ext_action(parse_explicit_expr))}, x0);
r = r.add({transition("@@", mk_ext_action(parse_partial_explicit_expr))}, x0);
r = r.add({transition("@&", mk_ext_action(parse_borrowed_expr))}, x0);
r = r.add({transition("sorry", mk_ext_action(parse_sorry))}, x0);
r = r.add({transition("match", mk_ext_action(parse_match))}, x0);
r = r.add({transition("nomatch", mk_ext_action(parse_nomatch))}, x0);
r = r.add({transition("do", mk_ext_action(parse_do_expr))}, x0);
r = r.add({transition("parser!", mk_ext_action(parse_lparser))}, x0);
r = r.add({transition("tparser!", mk_ext_action(parse_tparser))}, x0);
r = r.add({transition("panic!", mk_ext_action(parse_panic))}, x0);
r = r.add({transition("trace!", mk_ext_action(parse_trace))}, x0);
r = r.add({transition("`(", mk_ext_action_core(parse_stx_quot))}, x0);
r = r.add({transition("match_syntax", mk_ext_action(parse_match_syntax))}, x0);
return r;
}
parse_table init_led_table() {
parse_table r(false);
r = r.add({transition("->", mk_expr_action(get_arrow_prec()-1))}, mk_arrow(mk_bvar(1), mk_bvar(1)));
return r;
}
static parse_table * g_nud_table = nullptr;
static parse_table * g_led_table = nullptr;
parse_table get_builtin_nud_table() {
return *g_nud_table;
}
parse_table get_builtin_led_table() {
return *g_led_table;
}
void initialize_builtin_exprs() {
g_no_universe_annotation = new name("no_univ");
register_annotation(*g_no_universe_annotation);
g_do_failure_eq = new name("do_failure_eq");
register_annotation(*g_do_failure_eq);
g_infix_function = new name("infix_fn");
register_annotation(*g_infix_function);
g_not = new expr(mk_constant(get_not_name()));
g_nud_table = new parse_table();
*g_nud_table = init_nud_table();
g_led_table = new parse_table();
*g_led_table = init_led_table();
g_do_match_name = new name("_do_match");
g_let_match_name = new name("_let_match");
g_lambda_match_name = new name("_fun_match");
g_parser_checkpoint_have = new name{"parser", "checkpoint_have"};
register_bool_option(*g_parser_checkpoint_have, LEAN_DEFAULT_PARSER_CHECKPOINT_HAVE,
"(parser) introduces a checkpoint on have-expressions, checkpoints are like Prolog-cuts");
g_anonymous_constructor = new name("anonymousConstructor");
register_annotation(*g_anonymous_constructor);
}
void finalize_builtin_exprs() {
delete g_do_failure_eq;
delete g_infix_function;
delete g_led_table;
delete g_nud_table;
delete g_not;
delete g_do_match_name;
delete g_let_match_name;
delete g_lambda_match_name;
delete g_parser_checkpoint_have;
delete g_anonymous_constructor;
delete g_no_universe_annotation;
}
}
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