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Check for free variables in the environment before generalizing.

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This commit is contained in:
Danila Fedorin 2020-05-30 16:40:27 -07:00
parent 74f54abf5b
commit feeee2039b
4 changed files with 36 additions and 3 deletions
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9
12/type.cpp
View File

@ -185,3 +185,12 @@ void type_mgr::find_free(const type_ptr& t, std::set<std::string>& into) const {
for(auto& arg : app->arguments) find_free(arg, into); for(auto& arg : app->arguments) find_free(arg, into);
} }
} }
void type_mgr::find_free(const type_scheme_ptr& t, std::set<std::string>& into) const {
std::set<std::string> monotype_free;
find_free(t->monotype, monotype_free);
for(auto& not_free : t->forall) {
monotype_free.erase(not_free);
}
into.insert(monotype_free.begin(), monotype_free.end());
}

1
12/type.hpp
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@ -92,4 +92,5 @@ struct type_mgr {
type_ptr resolve(type_ptr t, type_var*& var) const; type_ptr resolve(type_ptr t, type_var*& var) const;
void bind(const std::string& s, type_ptr t); void bind(const std::string& s, type_ptr t);
void find_free(const type_ptr& t, std::set<std::string>& into) const; void find_free(const type_ptr& t, std::set<std::string>& into) const;
void find_free(const type_scheme_ptr& t, std::set<std::string>& into) const;
}; };

25
12/type_env.cpp
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@ -1,6 +1,22 @@
#include "type_env.hpp" #include "type_env.hpp"
#include "type.hpp" #include "type.hpp"
void type_env::find_free(const type_mgr& mgr, std::set<std::string>& into) const {
if(parent != nullptr) parent->find_free(mgr, into);
for(auto& binding : names) {
mgr.find_free(binding.second, into);
}
}
void type_env::find_free_except(const type_mgr& mgr, const std::string& avoid,
std::set<std::string>& into) const {
if(parent != nullptr) parent->find_free(mgr, into);
for(auto& binding : names) {
if(binding.first == avoid) continue;
mgr.find_free(binding.second, into);
}
}
type_scheme_ptr type_env::lookup(const std::string& name) const { type_scheme_ptr type_env::lookup(const std::string& name) const {
auto it = names.find(name); auto it = names.find(name);
if(it != names.end()) return it->second; if(it != names.end()) return it->second;
@ -33,9 +49,12 @@ void type_env::generalize(const std::string& name, type_mgr& mgr) {
if(names_it == names.end()) throw 0; if(names_it == names.end()) throw 0;
if(names_it->second->forall.size() > 0) throw 0; if(names_it->second->forall.size() > 0) throw 0;
std::set<std::string> free_variables; std::set<std::string> free_in_type;
mgr.find_free(names_it->second->monotype, free_variables); std::set<std::string> free_in_env;
for(auto& free : free_variables) { mgr.find_free(names_it->second->monotype, free_in_type);
find_free_except(mgr, name, free_in_env);
for(auto& free : free_in_type) {
if(free_in_env.find(free) != free_in_env.end()) continue;
names_it->second->forall.push_back(free); names_it->second->forall.push_back(free);
} }
} }

4
12/type_env.hpp
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@ -1,6 +1,7 @@
#pragma once #pragma once
#include <map> #include <map>
#include <string> #include <string>
#include <set>
#include "type.hpp" #include "type.hpp"
struct type_env; struct type_env;
@ -14,6 +15,9 @@ struct type_env {
type_env(type_env_ptr p) : parent(std::move(p)) {} type_env(type_env_ptr p) : parent(std::move(p)) {}
type_env() : type_env(nullptr) {} type_env() : type_env(nullptr) {}
void find_free(const type_mgr& mgr, std::set<std::string>& into) const;
void find_free_except(const type_mgr& mgr, const std::string& avoid,
std::set<std::string>& into) const;
type_scheme_ptr lookup(const std::string& name) const; type_scheme_ptr lookup(const std::string& name) const;
type_ptr lookup_type(const std::string& name) const; type_ptr lookup_type(const std::string& name) const;
void bind(const std::string& name, type_ptr t); void bind(const std::string& name, type_ptr t);