  Blockchains are decentralized systems that provide trustable execution
guarantees. Smart contracts are programs written in specialized programming
languages running on blockchains that govern how tokens and cryptocurrency are
sent and received. Smart contracts can invoke other smart contracts during the
execution of transactions always initiated by external users.
  Once deployed, smart contracts cannot be modified, so techniques like runtime
verification are very appealing for improving their reliability. However, the
conventional model of computation of smart contracts is transactional: once
operations commit, their effects are permanent and cannot be undone.
  In this paper, we proposed the concept of future monitors which allows
monitors to remain waiting for future transactions to occur before committing
or aborting. This is inspired by optimistic rollups, which are modern
blockchain implementations that increase efficiency (and reduce cost) by
delaying transaction effects. We exploit this delay to propose a model of
computation that allows (bounded) future monitors. We show our monitors correct
respect of legacy transactions, how they implement future bounded monitors and
how they guarantee progress. We illustrate the use of future bounded monitors
to implement correctly multi-transaction flash loans.
