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I have written a program in clojure but some of the functions have no arguments. What would be the advantages of coding such functions as a "def" instead of a "defn" with no arguments?
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A nullary or niladic function.
def is a special form that associates a symbol (x) in the current namespace with a value (7). This linkage is called a var . In most actual Clojure code, vars should refer to either a constant value or a function, but it's common to define and re-define them for convenience when working at the REPL.
This is a perfect opportunity to enforce encapsulation to avoid drowning the client in board-implementation details. Clojure has closures, and closures are an excellent way to group functions (Crockford 2008) with their supporting data.
(def t0 (System/currentTimeMillis)) (defn t1 [] (System/currentTimeMillis)) (t1) ;; => 1318408717941 t0 ;; => 1318408644243 t0 ;; => 1318408644243 (t1) ;; => 1318408719361 defs are evaluated only once whereas defns (with or without arguments) are evaluated (executed) every time they are called. So if your functions always return the same value, you can change them to defs but not otherwise.
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