Domain Modelling using Clojure

core.clj

(ns pms.core
  (:require [clojure.spec.alpha :as s]
            [clojure.spec.gen.alpha :as gen]
            [clojure.spec.test.alpha :as stest]))

(defrecord Sale [amount])
(defrecord Purchase [amount])

(defn non-blank-string? [x] (and (string? x) (not (clojure.string/blank? x))))

(s/def :project/id pos-int?)
(s/def :project/name (s/and string? seq))
(s/def :project/prj-list (s/and (s/coll-of ::project :gen-max 5) seq))

(s/def ::project
  (s/or :prj (s/keys :req-un [:project/id :project/name])
        :prj-group (s/keys :req-un [:project/name :project/prj-list])))

(s/def ::money double?)
(s/def :budget/income ::money)
(s/def :budget/expenditure ::money)
(s/def ::budget (s/keys :req-un [:budget/income :budget/expenditure]))

(s/def ::transaction (s/or :sale #(instance? % Sale)
                           :purchase #(instance? % Purchase)))

(s/def :report/budget-profit ::money)
(s/def :report/net-profit ::money)
(s/def :report/difference ::money)
(s/def ::report (s/keys :req-un [:report/budget-profit :report/net-profit :report/budget-profit]))

nil [{:keys [name prj-list] {:keys [budget-profit net-profit difference]}} & [indent]]
  (let [indent (or indent "")]
    (str name " - " "Budg.p.: " budget-profit " Net.p.: " net-profit " Diff.: " difference


(defmulti pp-project (fn [p & [indent]] (:id p)))
(defmethod pp-project nil [{:keys [name prj-list]
                            {:keys [budget-profit net-profit difference] :as report} :report}
                            & [indent]]
  (let [indent (or indent "")]
    (str name " - " "Budg.p.: " budget-profit " Net.p.: " net-profit " Diff.: " difference "\n"
     (apply str
            (for [p (butlast prj-list)]
              (str indent "|\n" indent "+-"
                   (pp-project p (str indent "| "))
                   "\n")))
     indent "|\n" indent "`-"
     (pp-project (last prj-list) (str indent "  ")))))

(defmethod pp-project :default [{:keys [id name]
                                 {:keys [budget-profit net-profit difference] :as report} :report}
                                 & [_]]
    (str " " name " [" id "] " "Budg.p.: " budget-profit " Net.p.: " net-profit " Diff.: " difference))

(defn get-budget [_]
  {:income (bigdec (/ (rand-int 1000000) 100)) :expenditure (bigdec (/ (rand-int 1000000) 100))})

(defn get-transactions [_]
  [(->Sale (bigdec (/ (rand-int 400000) 100))) (->Purchase (bigdec (/ (rand-int 400000) 100)))])

(defprotocol Transactable
  (transact [t]))

(extend-protocol Transactable
  Sale
  (transact [t]
    (:amount t))
  Purchase
  (transact [t]
    (-' (:amount t))))

(defn calculate-report [{:keys [income expenditure]} transactions]
  (let [budget-profit (- income expenditure)
        net-profit (reduce + (map transact transactions))]
    {:budget-profit budget-profit
     :net-profit net-profit
     :difference (- net-profit budget-profit)}))

(defmulti calculate-project-report :prj-list)

(defmethod calculate-project-report nil [p]
  (assoc p :report 
         (calculate-report (get-budget p) (get-transactions p))))

(defmethod calculate-project-report :default [p]
  (let [reported-prj-list (map calculate-project-report (:prj-list p))]
    (assoc p :report
           (reduce (partial merge-with +) (map :report reported-prj-list))
           :prj-list reported-prj-list)))

(def some-project
  {:name "Sweden"
   :prj-list [{:name "Stockholm"
               :prj-list [{:id 1 :name "Djurgaarden"}
                          {:id 2 :name "Skaergaarden"}]}
              {:id 3
               :name "Gothenborg"}
              {:name "Malmo"
               :prj-list [{:name "Malmo City"
                           :prj-list [{:id 41 :name "Fosie1"}
                                      {:id 42 :name "Fosie2"}
                                      {:name "Fosie3"
                                      :prj-list [{:id 31 :name "Djurgaarden"}
                                                 {:id 32 :name "Skaergaarden"}]}
                                      {:id 5 :name "Rosengaard"}]}
                          {:name "Limhamn"
                           :prj-list [{:id 6 :name "Kalkbrottet"}
                                      {:id 7 :name "Sibbarp"}]}]}
                {:id 4
                 :name "Eskilstuna"}
              ]})

(print (pp-project (calculate-project-report some-project)))

(print (pp-project (calculate-project-report (first (gen/sample (s/gen ::project) 1)))))

project.clj

(defproject pms "0.1.0-SNAPSHOT"
  :description "FIXME: write description"
  :url "http://example.com/FIXME"
  :license {:name "Eclipse Public License"
            :url "http://www.eclipse.org/legal/epl-v10.html"}
  :dependencies [[org.clojure/clojure "1.9.0"]
                 [org.clojure/spec.alpha "0.1.143"]]
  :main ^:skip-aot pms.core
  :target-path "target/%s"
  :profiles {:uberjar {:aot :all}
             :dev {:dependencies [[org.clojure/test.check "0.9.0"]]}})

Looking back at this, I love how you added more projects with good names. 👍