- if (!ly_is_procedure (new_value)
- && !is_simple_closure (new_value))
- ok = type_check_assignment (symbol, new_value,
- ly_symbol2scm ("backend-type?"));
+ bool pc = is_unpure_pure_container (new_value);
+ SCM vals[] = {pc ? unpure_pure_container_unpure_part (new_value) : new_value,
+ pc ? unpure_pure_container_pure_part (new_value) : SCM_BOOL_F
+ };
+
+ for (int i = 0; i < 2; i++)
+ if (!ly_is_procedure (vals[i])
+ && !is_simple_closure (vals[i]))
+ ok = ok && type_check_assignment (symbol, vals[i],
+ ly_symbol2scm ("backend-type?"));