Switch to using type schemes and implement polymorphism in compiler series

10/type.hpp

@@ -1,6 +1,8 @@
 #pragma once
 #include <memory>
 #include <map>
+#include <vector>
+#include <set>
 
 struct type_mgr;
 
@@ -12,6 +14,18 @@ struct type {
 
 using type_ptr = std::shared_ptr<type>;
 
+struct type_scheme {
+    std::vector<std::string> forall;
+    type_ptr monotype;
+
+    type_scheme(type_ptr type) : forall(), monotype(std::move(type)) {}
+
+    void print(const type_mgr& mgr, std::ostream& to) const;
+    type_ptr instantiate(type_mgr& mgr) const;
+};
+
+using type_scheme_ptr = std::shared_ptr<type_scheme>;
+
 struct type_var : public type {
     std::string name;
 
@@ -62,4 +76,5 @@ struct type_mgr {
     void unify(type_ptr l, type_ptr r);
     type_ptr resolve(type_ptr t, type_var*& var) const;
     void bind(const std::string& s, type_ptr t);
+    void find_free(const type_ptr& t, std::set<std::string>& into) const;
 };