michael/lean2
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Fix bug in ho_unifier

Browse source 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
This commit is contained in:
Leonardo de Moura 2013-09-19 13:37:28 -07:00
parent 959503a69f
commit d7cc5d2404
2 changed files with 23 additions and 12 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

25
src/library/ho_unifier.cpp
View file

@ -236,6 +236,19 @@ class ho_unifier::imp {
bool failed() const { return m_failed; }
};
/**
\brief Create the term (fun (x_0 : types[0]) ... (x_{n-1} : types[n-1]) body)
*/
expr mk_lambda(buffer<expr> const & types, expr const & body) {
expr r = body;
unsigned i = types.size();
while (i > 0) {
--i;
r = ::lean::mk_lambda(name(g_x_name, i), types[i], r);
}
return r;
}
/**
\brief Process a constraint <tt>ctx |- a = b</tt> where \c a is of the form <tt>(?m ...)</tt>.
We perform a "case split" using "projection" or "imitation". See Huet&Lang's paper on higher order matching
@ -264,12 +277,10 @@ class ho_unifier::imp {
m_state_stack.pop_back();
// add projections
for (unsigned i = 1; i < num_a; i++) {
expr proj = mk_var(i - 1);
for (unsigned j = 1; j < num_a; j++)
proj = mk_lambda(name(g_x_name, j), arg_types[j - 1], proj);
cqueue new_q = q;
new_q.push_front(constraint(ctx, arg(a, i), b));
metavar_env new_s = s;
expr proj = mk_lambda(arg_types, mk_var(num_a - i - 1));
new_s.assign(midx, proj);
m_state_stack.push_back(mk_state(new_s, new_q));
}
@ -294,17 +305,13 @@ class ho_unifier::imp {
imitation_args.push_back(mk_app(h_app_var_args.size(), h_app_var_args.data()));
new_q.push_front(constraint(ctx, mk_app(h_app_subst_args.size(), h_app_subst_args.data()), arg(b, i)));
}
expr imitation = mk_app(imitation_args.size(), imitation_args.data());
for (unsigned j = 1; j < num_a; j++)
imitation = mk_lambda(name(g_x_name, j), arg_types[j - 1], imitation);
expr imitation = mk_lambda(arg_types, mk_app(imitation_args.size(), imitation_args.data()));
new_s.assign(midx, imitation);
m_state_stack.push_back(mk_state(new_s, new_q));
} else {
// TODO(Leo) handle eq like we handle applications
// make f_a the constant function
expr imitation = lift_free_vars(b, 0, num_a - 1);
for (unsigned j = 1; j < num_a; j++)
imitation = mk_lambda(name(g_x_name, j), arg_types[j - 1], imitation);
expr imitation = mk_lambda(arg_types, lift_free_vars(b, 0, num_a - 1));
new_s.assign(midx, imitation);
m_state_stack.push_back(mk_state(new_s, new_q));
}

10
src/tests/library/ho_unifier.cpp
View file

@ -16,20 +16,24 @@ void tst1() {
metavar_env menv;
ho_unifier unify(env);
expr N = Const("N");
expr M = Const("M");
env.add_var("N", Type());
env.add_var("f", N >> (N >> N));
env.add_var("M", Type());
env.add_var("f", N >> (M >> M));
env.add_var("a", N);
env.add_var("b", N);
env.add_var("b", M);
expr f = Const("f");
expr x = Const("x");
expr a = Const("a");
expr b = Const("b");
expr m1 = menv.mk_metavar();
expr m2 = menv.mk_metavar();
expr l = m1(b);
expr l = m1(b, a);
expr r = f(b, f(a, b));
for (auto sol : unify(context(), l, r, menv)) {
std::cout << m1 << " -> " << beta_reduce(sol.first.get_subst(m1)) << "\n";
std::cout << beta_reduce(instantiate_metavars(l, sol.first)) << "\n";
lean_assert(beta_reduce(instantiate_metavars(l, sol.first)) == r);
std::cout << "--------------\n";
}
}