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feat(frontends/lean/calc_proof_elaborator): try conservative alternatives first

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This commit is contained in:
Leonardo de Moura 2015-01-31 21:29:34 -08:00
parent 87570740e2
commit 855050e623
2 changed files with 50 additions and 24 deletions
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2
hott/algebra/precategory/basic.hlean
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@ -22,7 +22,7 @@ namespace precategory
include C
attribute homH [instance]
definition compose := comp
definition compose [reducible] := comp
definition id [reducible] {a : ob} : hom a a := ID a

58
src/frontends/lean/calc_proof_elaborator.cpp
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@ -187,38 +187,64 @@ constraint mk_calc_proof_cnstr(environment const & env, options const & opts,
bool conservative = false;
return try_alternative(e, e_type, new_cs, conservative);
} else {
// TODO(Leo): after we have the simplifier and rewriter tactic, we should revise
// this code. It is "abusing" the higher-order unifier.
{
// Try the following possible intrepretations using a "conservative" unification procedure.
// That is, we only unfold definitions marked as reducible.
// Assume pr is the proof provided.
// 1. pr
bool conservative = true;
try { return try_alternative(e, e_type, new_cs, conservative); } catch (exception & ex) {}
// 2. eq.symm pr
constraint_seq symm_cs = new_cs;
auto symm = apply_symmetry(env, ctx, ngen, tc, e, e_type, symm_cs, g);
if (symm) {
try { return try_alternative(symm->first, symm->second, symm_cs, conservative); } catch (exception &) {}
}
// 3. subst pr (eq.refl lhs)
constraint_seq subst_cs = new_cs;
if (auto subst = apply_subst(env, ctx, ngen, tc, e, e_type, meta_type, subst_cs, g)) {
try { return try_alternative(subst->first, subst->second, subst_cs, conservative); } catch (exception&) {}
}
// 4. subst (eq.symm pr) (eq.refl lhs)
if (symm) {
constraint_seq subst_cs = symm_cs;
if (auto subst = apply_subst(env, ctx, ngen, tc, symm->first, symm->second, meta_type, subst_cs, g)) {
try { return try_alternative(subst->first, subst->second, subst_cs, conservative); } catch (exception&) {}
}
}
}
{
// Try the following possible insterpretations using the default unification procedure.
// 1. pr
bool conservative = false;
std::unique_ptr<throwable> saved_ex;
try {
bool conservative = false;
return try_alternative(e, e_type, new_cs, conservative);
} catch (exception & ex) {
saved_ex.reset(ex.clone());
}
// 2. eq.symm pr
constraint_seq symm_cs = new_cs;
auto symm = apply_symmetry(env, ctx, ngen, tc, e, e_type, symm_cs, g);
if (symm) {
bool conservative = false;
try { return try_alternative(symm->first, symm->second, symm_cs, conservative); } catch (exception &) {}
}
constraint_seq subst_cs = new_cs;
if (auto subst = apply_subst(env, ctx, ngen, tc, e, e_type, meta_type, subst_cs, g)) {
bool conservative = true;
try { return try_alternative(subst->first, subst->second, subst_cs, conservative); } catch (exception&) {}
}
if (symm) {
constraint_seq subst_cs = symm_cs;
bool conservative = true;
if (auto subst = apply_subst(env, ctx, ngen, tc, symm->first, symm->second, meta_type, subst_cs, g)) {
try { return try_alternative(subst->first, subst->second, subst_cs, conservative); } catch (exception&) {}
}
}
// We use the exception for the first alternative as the error message
saved_ex->rethrow();
lean_unreachable();
}
}
};
bool owner = false;
return mk_choice_cnstr(m, choice_fn, to_delay_factor(cnstr_group::Epilogue), owner, j, relax);