lang: ast: replace ast node print callback with to_string

lang/ast/int.c

@@ -1,18 +1,18 @@
 #include "ctx.h"
 #include "node.h"
 
-#include <stdio.h>
+#include <blue/object/string.h>
 
-static void print(struct ivy_ast_node *node)
+static void to_string(struct ivy_ast_node *node, b_string *str)
 {
 	struct ivy_ast_int_node *v = (struct ivy_ast_int_node *)node;
 
-	printf("%s (%llu)\n", ivy_ast_node_type_to_string(node->n_type),
+	b_string_append_cstrf(str, "%s (%llu)", ivy_ast_node_type_to_string(node->n_type),
 	       v->n_value->t_int);
 }
 
 struct ast_node_type int_node_ops = {
-	.n_print = print,
+	.n_to_string = to_string,
 	.n_state_size = sizeof(struct parser_state),
 	.n_node_size = sizeof(struct ivy_ast_int_node),
 };