The creator of Zig is a dope dude, one of the best Killer Queen players to have played the game.

Take this example for instance:

fn doMath(x: anytype) @TypeOf(x) {
  // …
}

There is no way to know what that function requires as input.

Of course you can’t know. That function has no requirements. As such there’s only one thing it can do… return x. Anything else is making an assumption about the parameter being passed.