Chris Devine ChrisDevo

## keybase.md

      
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                ChrisDevo
                / keybase.md
            
            
              Created
              March 5, 2021 20:28
            
          
    Keybase proof

I hereby claim:

I am chrisdevo on github.
I am cdevine (https://keybase.io/cdevine) on keybase.
I have a public key ASCvYbpoCYfH8XuuFnatt5-l9FYF0isQoP1qAfZrISrWiAo

To claim this, I am signing this object:

  
## pre_assertion_gist.clj
;; Using `assert` in :pre doesn't work because `(assert true)` returns `nil`.
;; :pre expects a truthy value, not `nil`.
;; Even though `clojure.test/is` is technically 'test' code (which usually doesn't appear in production code),
;; in this case it provides the behavior I want (custom error messages when validating funtion arguments)
;; with little overhead.

;; Using `assert`
(defn my-fn [bool]
  {:pre [(assert bool (format "Custom message returning modified value of bool: %s" (not bool)))]}
  (println bool))
	;; Using `assert` in :pre doesn't work because `(assert true)` returns `nil`.
	;; :pre expects a truthy value, not `nil`.
	;; Even though `clojure.test/is` is technically 'test' code (which usually doesn't appear in production code),
	;; in this case it provides the behavior I want (custom error messages when validating funtion arguments)
	;; with little overhead.

	;; Using `assert`
	(defn my-fn [bool]
	{:pre [(assert bool (format "Custom message returning modified value of bool: %s" (not bool)))]}
	(println bool))