We need a PPX lens generator

[foretspaisibles]

It would save a lot of boilerplate code – and make lenses a ridiculously useful feature – to have a PPX extension allowing to automatic lenses generation, so that we could write

type car = {
    make : string;
    model: string;
    mileage: int;
  } [@@lens]

and have automatically make_lens etc. defined for us.