Following https://github.com/Robert-van-Engelen/tinylisp (https://github.com/Robert-van-Engelen/tinylisp/blob/main/tinylisp.pdf)
How could I do NaN boxing in hare
example C code:

```
#define I unsigned
#define L double

/*** with NaN Boxing ***/
L box(I t,I i) { L x; *(uint64_t*)&x = (uint64_t)t<<48|i; return x; }
I ord(L x) { return *(uint64_t*)&x; }

```

I'm not sure what NaN boxing is, but the same code rewritten to use
Hare-style casts et al should work the same way I think.