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Add (relaxed) version of instantiate that can substitute terms containing free variables

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Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
This commit is contained in:
Leonardo de Moura 2013-08-03 11:45:51 -07:00
parent 2972bdfec3
commit 190855ad1b
4 changed files with 36 additions and 16 deletions
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18
src/kernel/instantiate.cpp
View file

@ -9,7 +9,7 @@ Author: Leonardo de Moura
#include "replace.h"
namespace lean {
expr instantiate(unsigned n, expr const * s, expr const & e) {
expr instantiate_with_closed(unsigned n, expr const * s, expr const & e) {
lean_assert(std::all_of(s, s+n, closed));
auto f = [=](expr const & e, unsigned offset) -> expr {
@ -24,7 +24,21 @@ expr instantiate(unsigned n, expr const * s, expr const & e) {
}
return e;
};
return replace_fn<decltype(f)>(f)(e);
}
expr instantiate(unsigned n, expr const * s, expr const & e) {
auto f = [=](expr const & e, unsigned offset) -> expr {
if (is_var(e)) {
unsigned vidx = var_idx(e);
if (vidx >= offset) {
if (vidx < offset + n)
return lift_free_vars(s[n - (vidx - offset) - 1], offset);
else
return var(vidx - n);
}
}
return e;
};
return replace_fn<decltype(f)>(f)(e);
}
}

7
src/kernel/instantiate.h
View file

@ -13,6 +13,13 @@ namespace lean {
\pre s[0], ..., s[n-1] must be closed expressions (i.e., no free variables).
*/
expr instantiate_with_closed(unsigned n, expr const * s, expr const & e);
inline expr instantiate_with_closed(expr const & s, expr const & e) { return instantiate_with_closed(1, &s, e); }
/**
\brief Replace the free variables with indices 0,...,n-1 with s[n-1],...,s[0] in e.
*/
expr instantiate(unsigned n, expr const * s, expr const & e);
inline expr instantiate(expr const & s, expr const & e) { return instantiate(1, &s, e); }
}

13
src/kernel/type_check.cpp
View file

@ -7,6 +7,7 @@ Author: Leonardo de Moura
#include <sstream>
#include "type_check.h"
#include "normalize.h"
#include "instantiate.h"
#include "free_vars.h"
#include "exception.h"
#include "trace.h"
@ -83,23 +84,19 @@ class infer_type_fn {
case expr_kind::Var: return lookup(ctx, var_idx(e));
case expr_kind::Type: return type(ty_level(e) + 1);
case expr_kind::App: {
expr f_t = infer_pi(arg(e, 0), ctx);
expr f = arg(e, 0);
unsigned i = 1;
unsigned num = num_args(e);
lean_assert(num >= 2);
while (true) {
expr const & c = arg(e, i);
expr f_t = infer_pi(f, ctx);
expr c_t = infer_type(c, ctx);
check_type(e, i, abst_domain(f_t), c_t, ctx);
// Remark: if f_t is an arrow, we don't have to call normalize and
// lower_free_vars
f_t = normalize(abst_body(f_t), ctx, c);
f_t = lower_free_vars(f_t, 1);
f = instantiate(abst_body(f_t), c);
i++;
if (i == num)
return f_t;
if (!is_pi(f_t))
throw exception("function expected");
return f;
}
}
case expr_kind::Lambda: {

14
src/tests/kernel/replace.cpp
View file

@ -30,13 +30,15 @@ static void tst1() {
static void tst2() {
expr r = lambda("x", type(level()), app(var(0), var(1), var(2)));
std::cout << instantiate(constant("a"), r) << std::endl;
lean_assert(instantiate(constant("a"), r) == lambda("x", type(level()), app(var(0), constant("a"), var(1))));
lean_assert(instantiate(constant("b"), instantiate(constant("a"), r)) ==
std::cout << instantiate_with_closed(constant("a"), r) << std::endl;
lean_assert(instantiate_with_closed(constant("a"), r) == lambda("x", type(level()), app(var(0), constant("a"), var(1))));
lean_assert(instantiate_with_closed(constant("b"), instantiate_with_closed(constant("a"), r)) ==
lambda("x", type(level()), app(var(0), constant("a"), constant("b"))));
std::cout << instantiate(constant("a"), abst_body(r)) << std::endl;
lean_assert(instantiate(constant("a"), abst_body(r)) == app(constant("a"), var(0), var(1)));
}
std::cout << instantiate_with_closed(constant("a"), abst_body(r)) << std::endl;
lean_assert(instantiate_with_closed(constant("a"), abst_body(r)) == app(constant("a"), var(0), var(1)));
std::cout << instantiate(var(10), r) << std::endl;
lean_assert(instantiate(var(10), r) == lambda("x", type(level()), app(var(0), var(11), var(1))));
}
int main() {
continue_on_violation(true);