Clojure assert not nil at compile time?

Question

We can see in Clojure a way to use design by contract to check that arguments to a function in Clojure are not-nil at runtime.

(defn constrained-fn [ x]
  {:pre  [(not (nil? x))]}
  x)
(constrained-fn nil)
=> AssertionError Assert failed: (not (nil? x))  ...../constrained-fn (form-init5503436370123861447.clj:1)

We can see a way to check the type of an expression at compile time in Clojure

(defmacro typeof 
  ([expression]
    (:class (expression-info expression)))

(defmacro primitive? 
  ([expression]
    (:primitive? (expression-info expression))))

Here is my take on the question based on compile-time macros in Clojure:

(defmacro compile-time-nil-check [x] (assert (not (nil? x))))
(def my-nullable nil)
(compile-time-nil-check my-nullable)

My question is - is there a way to check that a 'constant' is not nil at compile time in Clojure?

(I realise this question might seem trivial- I want to use it as a building block for a subsequent question about compile-time type checks in Clojure).

Answer 1

If by 'constant' you mean something stored in a global var

(def my-nullable nil)

that can be resolved at compile-time, then:

(defmacro compile-time-var-nil-check [x] 
  (let [x @(resolve x)] 
    (assert (not (nil? x)))))