gistfile1.txt

;; This buffer is for Clojure experiments and evaluation.
;; Press C-j to evaluate the last expression.

;; (ns test1
;;   (:require
;;    [cats.core :as c]
;;    [cats.monad.either :as either]))

;; (defn check-logged-out []
;;   (if true
;;     (either/right)
;;     (either/left {:error :logged-out})))

;; (defn check-params [params]
;;   (if true
;;     (either/right)
;;     (either/left {:error :wrong-params})))

;; (defn check-authentication [user params]
;;   (if false
;;     (either/right)
;;     (either/left {:error :wrong-login-or-pass})))

;; (defn find-user [params]
;;   (if true
;;     (either/right :user)
;;     (either/left)))

;; (defn log-in! [user]
;;   (assert (= :user user)))


;; (time
;;  (dotimes [_ 1000000]
;;    (let [params nil]
;;      (c/mlet [_ (check-logged-out)
;;               _ (check-params params)
;;               user (find-user params)
;;               _ (check-authentication user params)]
;;              (log-in! user)
;;              (c/return {:success true})))))







;; (ns test2
;;   (:require
;;    [slingshot.slingshot :as s]))

;; (defn check-logged-out []
;;   (if true
;;     nil
;;     (s/throw+ {:error :logged-out})))

;; (defn check-params [params]
;;   (if true
;;     nil
;;     (s/throw+ {:error :wrong-params})))

;; (defn check-authentication [user params]
;;   (if false
;;     nil
;;     (s/throw+ {:error :wrong-login-or-pass})))

;; (defn find-user [params]
;;   :user)

;; (defn log-in! [user]
;;   (assert (= :user user)))


;; (time
;;  (dotimes [_ 1000000]
;;    (let [params nil]
;;      (s/try+
;;       (let [_ (check-logged-out)
;;             _ (check-params params)
;;             user (find-user params)
;;             _ (check-authentication user params)]
;;         (log-in! user)
;;         {:success true})
;;       (catch Object e e)))))
   





;; (ns test3)

;; (defmacro let-cond [bindings & body]
;;   (if (empty? bindings)
;;     `(do ~@body)
;;     (let [binding (take 2 bindings)
;;           bindings (drop 2 bindings)]
;;       (if (-> binding first seq?)
;;         `(if-let [~'% ~(first binding)]
;;            ~(second binding)
;;            (let-cond [~@bindings] ~@body))
;;         `(let [~@binding]
;;            (let-cond [~@bindings] ~@body))))))

;; (defn check-logged-out []
;;   (if-not true
;;     {:error :logged-out}))

;; (defn check-params [params]
;;   (if-not true
;;     {:error :wrong-params}))

;; (defn check-authentication [user params]
;;   (if-not false
;;     {:error :wrong-login-or-pass}))

;; (defn find-user [params]
;;   (if true
;;     :user))

;; (defn log-in! [user]
;;   (assert (= :user user)))


;; (time
;;  (dotimes [_ 1000000]
;;    (let [params nil]
;;      (let-cond [(check-logged-out) %
;;                 (check-params params) %
;;                 user (find-user params)
;;                 (check-authentication user params) %]
;;        (log-in! user)
;;        {:success true}))))














(ns test4)

(defn check-logged-out []
  (if true
    nil
    (throw (java.lang.RuntimeException. "logged-out"))))

(defn check-params [params]
  (if true
    nil
    (throw (java.lang.RuntimeException. "wrong-params"))))


(defn check-authentication [user params]
  (if false
    nil
    (throw (RuntimeException. "wrong-login-or-pass" nil true true))))

(defn find-user [params]
  :user)

(defn log-in! [user]
  (assert (= :user user)))


(time
 (dotimes [_ 1000000]
   (let [params nil]
     (try
      (let [_ (check-logged-out)
            _ (check-params params)
            user (find-user params)
            _ (check-authentication user params)]
        (log-in! user)
        {:success true})
      (catch RuntimeException e e)))))
   




(java.lang.RuntimeException.)

logic.clj

;; check-* return error map or nil

(defn process [params]
  (or (check-logged-out)
      (check-params params)
      (let [user (find-user params)]
        (or (check-authentication user params)
            (do (user-session/log-in! user)
                {:type ::processed :user user})))))

;; ---------------------------------

(defn process [params]
  (let [d-user (delay (find-user params))]
    (or (check-logged-out)
        (check-params params)
        (check-authentication @d-user params)
        (do (user-session/log-in! @d-user)
            {:type ::processed :user @d-user}))))

;; ---------------------------------

;; https://github.com/Engelberg/better-cond
(b/defnc process [params]
  :let [err (or (check-logged-out)
                (check-params params))]
  (some? err) err
  :let [user (find-user params)
        err  (check-authentication user params)]
  (some? err) err
  :do (user-session/log-in! user)
  {:type ::processed :user user}))))))

;; ---------------------------------

(defmacro let-cond [bindings & body]
  (if (empty? bindings)
    `(do ~@body)
    (let [binding (take 2 bindings)
          bindings (drop 2 bindings)]
      (if (-> binding first seq?)
        `(if-let [~'% ~(first binding)]
           ~(second binding)
           (let-cond [~@bindings] ~@body))
        `(let [~@binding]
           (let-cond [~@bindings] ~@body))))))

(defn process [params]
  (let-cond [(check-logged-out) %
             (check-params params) %
             user (find-user params)
             (check-authentication user params) %]
    (user-session/log-in! user)
    {:type ::processed :user user}))