title: Breaking out of monad sequence
body: <p>Is it possible to break out of a monad sequence?</p>
  
  <p>For instance, if I want to break out of a sequence earlier based on some condition calculated in the middle of the sequence. Say, in a 'do' notation I bind a value and based on the value I want to either finish the sequence or stop it. Is there something like  a 'pass' function?</p>
  
  <p>Thanks.</p>