cuik_tagged.c

// the macros could be made to not do
// anything on codebases that wanna support both
#ifdef __CUIK_C__
#include <cuik.h>
#else
#define cuik_tag
#define cuik_tagged(val)
#define cuik_try_use(a, b) ((a) == (b))
#define cuik_tag_switch switch
#endif

typedef enum ValueType {
    VAL_NUM,
    VAL_STRING
} ValueType;

typedef struct Value {
    cuik_tag ValueType tag;
    union {
        cuik_tagged(VAL_NUM) int num;
        cuik_tagged(VAL_STRING) char* str;
    };
} Value;

int add(Value v, int i) {
    // let's say it only works on numbers
    if (cuik_try_use(v.tag, VAL_NUM)) {
        // simply put, you can't access '.str' within here
        return v.num + i;
    }

    abort();
}

void print_val(const Value* v) {
    cuik_tag_switch (v->tag) {
    case VAL_NUM:
        printf("Number: %d\n", v->num);
        break;
    case VAL_STR:
        printf("String: '%s'\n", v->str);
        break;
    default:
        // considered an assertion in debug for me
        __builtin_unreachable();
    }
}