I'd be cool if one could leave runtime elements in there, for example leaving an intermediate value as x, with the C++ template magic reducing everything down t

I'd be cool if one could leave runtime elements in there, for example leaving an intermediate value as x, with the C++ template magic reducing everything down to producing the sequence of bytes with just one integer to be filled in. Then this could be used for on-the-fly code generation like you'd see in a jit-emulator like qemu.