Meltdown brings to Clojure the ease of reactive programming. Your code is now turned into a set of event definitions and listeners to those events. Your running code is now bound to a state (or a set of multiple states) and each part of the code, can now react from values of the state. The event stream becomes abstracted from the code.
Say you are implementing a brand new mail software; messages showing on your screen would be bound to a state or a part of the state. The visual representation of the e-mails is a direct translation of the state itself. If you need to replace or pull in new e-mails, you would add some messages to that state list.
Meltdown can also be used as a stream processing toolkit, meaning you can somehow pipe the processing of messages, and we will look at it in the last part of this recipe.