a little bit of cleanup

src/ast/ast.hpp

@@ -9,13 +9,7 @@ namespace ast {
         virtual ~node() = default;
     };
 
-    struct statement : node {
-        virtual std::string token_literal() const override = 0;
-        virtual std::string str() const override = 0;
-    };
+    struct statement : node {};
 
-    struct expression : node {
-        virtual std::string token_literal() const override = 0;
-        virtual std::string str() const override = 0;
-    };
+    struct expression : node {};
 } // namespace ast

src/parser/parser.cpp

@@ -1,8 +1,5 @@
 #include "parser.hpp"
 
-#include "ast/errors/error.hpp"
-#include "token/type.hpp"
-
 #include <sstream>
 
 namespace parser {

src/parser/parser.hpp

@@ -2,12 +2,15 @@
 
 #include "ast/ast.hpp"
 #include "ast/errors/error.hpp"
+#include "ast/program.hpp"
 #include "ast/statements/expression.hpp"
 #include "ast/statements/let.hpp"
 #include "ast/statements/return.hpp"
 #include "lexer/lexer.hpp"
 #include "token/token.hpp"
 
+#include <vector>
+
 namespace parser {
     struct parser {
         parser(lexer::lexer& lexer);