Decker heavily emphasizes the concept of "reified data", representing information as tangible entities within a deck.

You can create "contraptions" as specialized data containers/editors for specific applications:

http://beyondloom.com/decker/decker.html#customwidgets

For example, "WigglyKit" offers several contraptions which operate on a shared convention for representing animated images:

http://beyondloom.com/decker/wigglykit.html

You can also represent composite data as a series of cards in a deck, or use cards as encapsulated "objects" that you communicate with via events:

http://beyondloom.com/blog/sketchpad.html#cardsarerecords

In a pinch, you can also easily encode arbitrary data in fields as a JSON superset with their ".data" attribute.