Handle negative numbers in print

lib/print.c

@@ -7,12 +7,18 @@ size_t print(am_t *am, char *buffer, size_t buffer_size)
 	assert(am->val->is_atom);
 	assert(am->val->atom.type == ATOM_TYPE_INTEGER);
 
+	size_t i = 0;
+
 	int64_t value = am->val->atom.integer;
+	if (value < 0) {
+		buffer[i++] = '-';
+		value *= -1;
+	}
+
 	int divisor = 10;
 	while (divisor <= value)
 		divisor *= 10;
 
-	size_t i = 0;
 	do {
 		divisor /= 10;
 		const int digit = value / divisor;