Question

In clojure, I would like to write a defn-my macro that creates a function with a body. And when this function is executed, it exits on first statement that doesn’t return 0.

For example:

(defn f1[] (println "f1") 5)
(defn f2[] (println "f2") 0)
(defn-my foo[] (f1) (f2))     
(defn-my bar[] (f2) (f1))
(foo); should execute f1 and exit
(bar); should execute f2 and then f1

Answer 1

I think you are asking for something like this:

(defmacro and-zero
  ([] true)
  ([x] (zero? x))
  ([x & next] 
    `(let [and# (zero? ~x)]
       (if and# 
         (and-not-zero ~@next)
         and#))))

user=> (and-zero 0 0 0)
true
user=> (and-zero 0 1 0)
false

The macro assumes every expression evaluates to a number. It will throw an exception if, for example, an expression evaluates to nil.

Then you can write yout defn-my like this:

(defmacro defn-my [ & body ] `(and-zero ~@body))