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fix(frontends/lean/elaborator): more robust support for coercions to

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function-class that contains implicit arguments
This commit is contained in:
Leonardo de Moura 2014-09-16 13:08:34 -07:00
parent d0d23eb525
commit dffe9a6f17
2 changed files with 42 additions and 12 deletions
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44
src/frontends/lean/elaborator.cpp
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@ -336,6 +336,35 @@ public:
return mc.first;
}
static bool is_implicit_pi(expr const & e) {
if (!is_pi(e))
return false;
binder_info bi = binding_info(e);
return bi.is_strict_implicit() || bi.is_implicit();
}
expr add_implict_args(expr e, constraint_seq & cs, bool relax) {
type_checker & tc = *m_tc[relax];
constraint_seq new_cs;
expr type = tc.whnf(tc.infer(e, new_cs), new_cs);
if (!is_implicit_pi(type))
return e;
cs += new_cs;
while (true) {
lean_assert(is_pi(type));
tag g = e.get_tag();
bool is_strict = false;
expr imp_arg = mk_placeholder_meta(some_expr(binding_domain(type)), g, is_strict, cs);
e = mk_app(e, imp_arg, g);
type = instantiate(binding_body(type), imp_arg);
constraint_seq new_cs;
type = tc.whnf(type, new_cs);
if (!is_implicit_pi(type))
return e;
cs += new_cs;
}
}
/** \brief Make sure \c f is really a function, if it is not, try to apply coercions.
The result is a pair <tt>new_f, f_type</tt>, where new_f is the new value for \c f,
and \c f_type is its type (and a Pi-expression)
@ -362,7 +391,9 @@ public:
throw_kernel_exception(env(), f, [=](formatter const & fmt) { return pp_function_expected(fmt, f); });
} else if (is_nil(tail(coes))) {
expr old_f = f;
bool relax = m_relax_main_opaque;
f = mk_app(head(coes), f, f.get_tag());
f = add_implict_args(f, cs, relax);
f_type = infer_type(f, cs);
save_coercion_info(old_f, f);
lean_assert(is_pi(f_type));
@ -375,18 +406,7 @@ public:
list<constraints> choices = map2<constraints>(coes, [&](expr const & coe) {
expr new_f = copy_tag(f, ::lean::mk_app(coe, f));
constraint_seq cs;
while (true) {
expr new_f_type = m_tc[relax]->infer(new_f, cs);
if (!is_pi(new_f_type))
break;
binder_info bi = binding_info(new_f_type);
if (!bi.is_strict_implicit() && !bi.is_implicit())
break;
tag g = f.get_tag();
bool is_strict = false;
expr imp_arg = mk_placeholder_meta(some_expr(binding_domain(new_f_type)), g, is_strict, cs);
new_f = mk_app(new_f, imp_arg, g);
}
new_f = add_implict_args(new_f, cs, relax);
cs += mk_eq_cnstr(meta, new_f, j, relax);
return cs.to_list();
});

10
tests/lean/run/coe12.lean Normal file
View file

@ -0,0 +1,10 @@
import data.nat
inductive foo (A B : Type) : Type :=
mk : (Π {C : Type}, A → C → B) → foo A B
definition to_fun [coercion] {A B : Type} (f : foo A B) : Π {C : Type}, A → C → B :=
foo.rec (λf, f) f
variable f : foo nat nat
variable a : nat
check f a true