I don't know anything about PPXs, and I'm not even quite a do-notation pro, but I'd really like something like this in Reason

DoFuture.re

[%do Future]
do {
  user <- getUser("some_user_id")
  orders = user.orders
  firstOrderId <- orders |> List.head |> Future.fromOption
  order <- getOrder(firstOrderId)
  pure(user.firstName ++ " ordered a " ++ order.productName)
};

Future.(
  getUser("some_user_id")
  |> flatMap(user => {
    let orders = user.orders;
    orders |> List.head |> fromOption |> flatMap(firstOrderId => {
      getOrder(firstOrderId) |> Future.flatMap(order => {
        pure(user.firstName ++ "ordered a " ++ order.productName)
      })
    })
  })
)