#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <assert.h>

/*
 * Use typecast only when
 * ∙ safe… and you know why
 * ∙ necessary… and you know why
 */

int _compare_tree_nodes(const void* a_lhs, const void* a_rhs) { // 
    // OK
    // TreeNode* lhs_node = a_lhs;
    // TreeNode* rhs_node = a_rhs;

    // OK
    // Won't compile
    // return lhs_node -> frequency - rhs_node -> frequency;
    return ((TreeNode*)lhs_node) -> frequency - ((TreeNode*)rhs_node) -> frequency;
    // Necessary because the compiler doesn't know if ->frequency is appropriate for that addess.
    // Safe because you will only call this with TreeNode* arguments.
}

void append(int value, Node** a_head, Node** a_tail) {
    // …
}

int main(int argc, char* argv[]) {
    // BAD
    // TreeNode* new_node = (TreeNode*) malloc(sizeof(*new_node));  // unnecessary

    Node* head = NULL;
    Node* tail = NULL;
    append(3, (Node**)head, (Node**)tail);  // VERY BAD!!! Tells compiler not to warn you about your mistake.
    
    return EXIT_SUCCESS;
}
/* vim: set tabstop=4 shiftwidth=4 fileencoding=utf-8 noexpandtab: */