Rust's Option<T> and Result<T, E> implemented in C

option.c

#include <stdio.h>

#define Option_t(T) struct option__ ## T

#define Option_td(T) \
	Option_t(T) { \
		char some; \
		T value; \
	}

#define None(T) \
	((Option_t(T)){.some = 0})

#define Some(T, v) \
	((Option_t(T)){.some = 1, .value = v})

#define try_option(T, r) \
	({ \
		typeof(r) r_ = (r); \
		if (!r_.some) \
			return None(T); \
		(r_).value; \
	})

char b2c(char b)
{
	if (b)
		return 'T';
	else
		return 'F';
}

Option_td(int);
Option_t(int) divide(int x, int y)
{
	if (y != 0)
		return Some(int, x / y);
	else
		return None(int);
}

Option_td(char);
Option_t(char) divide_by_zero(int x)
{
	Option_t(int) r = divide(x, 0);
	int f = try_option(char, r);
	return Some(char, f + '0');
	/*return Ok(char, try_result(char, r) + '0');*/
}

Option_t(char) divide_by_two(int x)
{
	return Some(char, try_option(char, divide(x, 2)) + '0');
}

int main(void)
{
	Option_t(char) z = divide_by_zero(6);
	printf("Divide by zero: %c %c\n", b2c(z.some), z.value);

	Option_t(char) t = divide_by_two(6);
	printf("Divide by two: %c %c\n", b2c(t.some), t.value);

	return 0;
}

result.c

#include <stdio.h>

#define __Result_t(T, E) struct result__ ## T ## __ ## E
#define _Result_t(T, E) __Result_t(T, E)

#define _Result_td(T, E) \
	_Result_t(T, E) { \
		char success; \
		union { \
			T result; \
			E error; \
		}; \
	}

#define _Err(T, E, e) \
	((_Result_t(T, E)){.success = 0, .error = e})

#define _Ok(T, E, r) \
	((_Result_t(T, E)){.success = 1, .result = r})

#define _try_result(T, E, r) \
	({ \
		typeof(r) r_ = (r); \
		if (!r_.success) \
			return _Err(T, E, r_.error); \
		r_.result; \
	})

#ifndef RESULT_ERR_T
#define RESULT_ERR_T short
#endif // !RESULT_ERR_T

#define Result_t(T)  _Result_t(T, RESULT_ERR_T)
#define Result_td(T) _Result_td(T, RESULT_ERR_T)
#define Err(T, e)    _Err(T, RESULT_ERR_T, e)
#define Ok(T, r)     _Ok(T, RESULT_ERR_T, r)

#define try_result(T, r) _try_result(T, RESULT_ERR_T, r)

char b2c(char b)
{
	if (b)
		return 'T';
	else
		return 'F';
}

Result_td(int);
Result_t(int) divide(int x, int y)
{
	if (y != 0)
		return Ok(int, x / y);
	else
		return Err(int, -1);
}

Result_td(char);
Result_t(char) divide_by_zero(int x)
{
	Result_t(int) r = divide(x, 0);
	int f = try_result(char, r);
	return Ok(char, f + '0');
	/*return Ok(char, try_result(char, r) + '0');*/
}

Result_t(char) divide_by_two(int x)
{
	return Ok(char, try_result(char, divide(x, 2)) + '0');
}

int main(void)
{
	Result_t(char) z = divide_by_zero(6);
	printf("Divide by zero: %c %c %c\n", b2c(z.success), z.result, z.error);

	Result_t(char) t = divide_by_two(6);
	printf("Divide by two: %c %c %c\n", b2c(t.success), t.result, t.error);

	return 0;
}