Homoiconic

ClojureScript is a modern LISP, and LISPs are homoiconic.

You program in a LISP by creating and assembling LISP data structures. The syntax is data literals. Dwell on that for a moment. You are programming in data. The functions which later transform data, themselves start as data.

So, Clojurists place particular emphasis on the primacy of data.

They meditate on aphorisms like data is the ultimate in late binding. They exalt inequalities like data > functions > macros. (Disappointingly, they also re-watch Rich Hickey videos a bit too much and wish their hair was darker and more curly.)

I cannot stress enough what a big deal this is. It will seem like a syntax curiosity at first but, when the penny drops for you on this, it tends to be a profound moment.

So, it will come as no surprise, then, to find that re-frame has a data-oriented design. Events are data. Effects are data. DOM is data. The functions which transform data are registered and looked up via data. Interceptors (data) are preferred to middleware (higher order functions). Etc.

And re-frame apps are reactive which further elevates data because in reactive systems, it is the arrival of data which coordinates the calling of functions, not the other way around.

Data - that's the way we roll.