Obsidian: A safer blockchain programming language(obsidian-lang.com)

  main contract Policy {
    state Offered {
      int cost ;
      int expirationTime ;
    }
    state Active {}
    state Expired {}
    Policy@Offered ( int c , int expTime ) {
      -> Offered ( cost = c , expirationTime = expTime );
    }
    transaction activate ( Policy@Offered >> Active this ) {
      -> Active ;
    }
    transaction expire ( Policy@Offered >> Expired this ) {
      -> Expired ;
    }
  }