Fixed build errors.

language/main.cc

@@ -213,7 +213,7 @@ int repl(shared_ptr<Environment> env, bool print_ast)
             auto ret = run("(repl)", env, line.c_str(), line.size(), val, msgs, ast);
             if (ret) {
                 if (print_ast) {
-                    ast->print();
+                    AstPrint::print(ast);
                 }
                 cout << val << endl;
                 linenoise::AddHistory(line.c_str());
@@ -282,7 +282,7 @@ int main(int argc, const char** argv)
                 }
                 return -1;
             } else if (print_ast) {
-                ast->print();
+                AstPrint::print(ast);
             }
         }