1-project.clj

;; Dependency
[environ "1.1.0"]

;; Profiles
:profiles {:dev {:env {:dev "true"}}

2-core.cljs

(ns my-app.core
  (:require [my-app.macro-util :refer-macros [when-dev]]))

(defn init! []
  ; With other various setup code ...
  
  (when-dev
    (do
      (st/instrument)
      (verify-instrumentation!)))
  
  ; Recommended for good spec output
  (set! s/*explain-out* (expound/custom-printer {:show-valid-values? true})))

3-macro-utils.cljc

(ns my-app.macro-util
  (:require #?(:clj [environ.core :refer [env]])))

#?(:clj (defmacro if-fn [fun if-forms else-forms]
          (if (fun)
            if-forms
            else-forms)))

#?(:clj (defmacro if-dev [if-forms else-forms]
          `(if-fn ~#(some? (:dev env)) ~if-forms ~else-forms)))

#?(:clj (defmacro when-dev [if-forms]
          `(if-dev ~if-forms nil)))

#?(:clj (defmacro if-staging [if-forms else-forms]
          `(if-fn ~#(some? (:staging env)) ~if-forms ~else-forms)))

#?(:clj (defmacro when-staging [if-forms]
          `(if-staging ~if-forms nil)))

#?(:clj (defmacro if-prod [if-forms else-forms]
          `(if-fn ~#(some? (:production env)) ~if-forms ~else-forms)))

#?(:clj (defmacro when-prod [if-forms]
          `(if-prod ~if-forms nil)))