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feat(frontends/lean): 'using' expression without 'show' or 'have'

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closes #536
This commit is contained in:
Leonardo de Moura 2015-04-04 15:04:13 -07:00
parent fa33f706f8
commit 8c59f17605
2 changed files with 47 additions and 27 deletions
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66
src/frontends/lean/builtin_exprs.cpp
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@ -282,6 +282,43 @@ static expr parse_proof_qed_core(parser & p, pos_info const & pos) {
return r;
}
static expr parse_proof(parser & p, expr const & prop);
static expr parse_using_expr(parser & p, expr const & prop, pos_info const & using_pos) {
parser::local_scope scope(p);
buffer<expr> locals;
buffer<expr> new_locals;
while (!p.curr_is_token(get_comma_tk())) {
auto id_pos = p.pos();
expr l = p.parse_id();
if (!is_local(l))
throw parser_error("invalid 'using' declaration for 'have', local expected", id_pos);
expr new_l = l;
binder_info bi = local_info(l);
if (!bi.is_contextual())
new_l = update_local(l, bi.update_contextual(true));
p.add_local(new_l);
locals.push_back(l);
new_locals.push_back(new_l);
}
p.next(); // consume ','
expr pr = parse_proof(p, prop);
unsigned i = locals.size();
while (i > 0) {
--i;
expr l = locals[i];
expr new_l = new_locals[i];
pr = p.save_pos(Fun(new_l, pr), using_pos);
pr = p.save_pos(mk_app(pr, l), using_pos);
}
return pr;
}
static expr parse_using(parser & p, unsigned, expr const *, pos_info const & pos) {
expr prop = p.save_pos(mk_expr_placeholder(), pos);
return parse_using_expr(p, prop, pos);
}
static expr parse_proof(parser & p, expr const & prop) {
if (p.curr_is_token(get_from_tk())) {
// parse: 'from' expr
@ -304,33 +341,7 @@ static expr parse_proof(parser & p, expr const & prop) {
// parse: 'using' locals* ',' proof
auto using_pos = p.pos();
p.next();
parser::local_scope scope(p);
buffer<expr> locals;
buffer<expr> new_locals;
while (!p.curr_is_token(get_comma_tk())) {
auto id_pos = p.pos();
expr l = p.parse_id();
if (!is_local(l))
throw parser_error("invalid 'using' declaration for 'have', local expected", id_pos);
expr new_l = l;
binder_info bi = local_info(l);
if (!bi.is_contextual())
new_l = update_local(l, bi.update_contextual(true));
p.add_local(new_l);
locals.push_back(l);
new_locals.push_back(new_l);
}
p.next(); // consume ','
expr pr = parse_proof(p, prop);
unsigned i = locals.size();
while (i > 0) {
--i;
expr l = locals[i];
expr new_l = new_locals[i];
pr = p.save_pos(Fun(new_l, pr), using_pos);
pr = p.save_pos(mk_app(pr, l), using_pos);
}
return pr;
return parse_using_expr(p, prop, using_pos);
} else {
throw parser_error("invalid expression, 'by', 'begin', 'proof', 'using' or 'from' expected", p.pos());
}
@ -600,6 +611,7 @@ parse_table init_nud_table() {
r = r.add({transition("!", mk_ext_action(parse_consume_args_expr))}, x0);
r = r.add({transition("begin", mk_ext_action_core(parse_begin_end))}, x0);
r = r.add({transition("proof", mk_ext_action(parse_proof_qed))}, x0);
r = r.add({transition("using", mk_ext_action(parse_using))}, x0);
r = r.add({transition("sorry", mk_ext_action(parse_sorry))}, x0);
r = r.add({transition("match", mk_ext_action(parse_match))}, x0);
init_structure_instance_parsing_rules(r);

8
tests/lean/run/using_expr.lean Normal file
View file

@ -0,0 +1,8 @@
example (p q : Prop) (H : p ∧ q) : p ∧ q ∧ p :=
have Hp : p, from and.elim_left H,
have Hq : q, from and.elim_right H,
using Hp Hq,
begin
apply and.intro, assumption,
apply and.intro, assumption
end