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fix(library/fo_unify): unify (?f ?x) with (g a b)

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We flat applications. So, (g a b) is actually ((g a) b).
So, we must be able to unify (?f ?x) with (g a b).
Solution:
        ?g <- (g a)
        ?x <- b

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
This commit is contained in:
Leonardo de Moura 2013-12-07 10:25:04 -08:00
parent a75d05fdb4
commit 5f3b9dbbbd
1 changed files with 13 additions and 7 deletions
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20
src/library/fo_unify.cpp
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@ -28,7 +28,7 @@ optional<substitution> fo_unify(expr e1, expr e2) {
lean_assert(e1);
lean_assert(e2);
substitution s;
unsigned i;
unsigned i1, i2;
expr lhs1, rhs1, lhs2, rhs2;
buffer<expr_pair> todo;
todo.emplace_back(e1, e2);
@ -52,12 +52,18 @@ optional<substitution> fo_unify(expr e1, expr e2) {
case expr_kind::Var: case expr_kind::Constant: case expr_kind::Type: case expr_kind::Value: case expr_kind::MetaVar:
return optional<substitution>();
case expr_kind::App:
if (num_args(e1) != num_args(e2))
return optional<substitution>();
i = num_args(e1);
while (i > 0) {
--i;
todo.emplace_back(arg(e1, i), arg(e2, i));
i1 = num_args(e1);
i2 = num_args(e2);
while (i1 > 0 && i2 > 0) {
--i1;
--i2;
if (i1 == 0 && i2 > 0) {
todo.emplace_back(arg(e1, i1), mk_app(i2+1, begin_args(e2)));
} else if (i2 == 0 && i1 > 0) {
todo.emplace_back(mk_app(i1+1, begin_args(e1)), arg(e2, i2));
} else {
todo.emplace_back(arg(e1, i1), arg(e2, i2));
}
}
break;
case expr_kind::Eq: