Add specter file and deps

Adding some koans for specter and eidolon

project.clj

@@ -1,7 +1,9 @@
 (defproject clojure-koans "0.5.2-SNAPSHOT"
   :description "The Clojure koans."
   :dependencies [[org.clojure/clojure "1.10.0"]
-                 [koan-engine "0.2.5"]]
+                 [koan-engine "0.2.5"]
+                 [com.rpl/specter "1.1.3"]
+                 [eidolon "0.1.0"]]
   :dev-dependencies [[lein-koan "0.1.5"]]
   :profiles {:dev {:dependencies [[lein-koan "0.1.5"]]}}
   :repl-options {:init-ns koan-engine.runner

src/koans/28_specter.clj

@@ -0,0 +1,89 @@
+(ns koans.28-specter
+  (:require [koan-engine.core :refer :all]
+            [com.rpl.specter :as sr]
+            [eidolon.core :as e]))
+
+;; Imagine you own a car dealership and manage your inventory with a clojure map 
+(def car-inventory
+  {:cars {:ford {:focus [{:doors 2
+                          :color "red"}
+                         {:doors 2
+                          :color "blue"}]
+                 :expedition [{:doors 4
+                               :color "red"}
+                              {:doors 4
+                               :color "black"}]}
+          :toyota {:camry [{:doors 2
+                            :color "red"}
+                           {:doors 4
+                            :color "tan"}]
+                   :rav4  [{:doors 4
+                            :color "blue"}
+                           {:doors 4
+                            :color "blue"}]}
+          :latacara {:prime [{:doors 11
+                              :color "clear"}]
+                     :prime-zero [{:doors 0
+                                   :color "red"}
+                                  {:doors 0
+                                   :color "green"}]}}})
+
+(def car-inventory-ford-focus
+  {:car {:ford {:focus [{:doors 2
+                         :color "red"}
+                        {:doors 2
+                         :color "blue"}]}}})
+
+;; The hope of this exercise is to get you more familiar with specter and eidolon
+
+(meditations
+
+ ;; Imagine you wanted to select the keys for all of the brands of cars you own
+ ;; Try doing this without specter
+ (= [:ford :toyota :latacara]
+    (__ (get car-inventory __)))
+
+ ;; Now try with specter!
+ (= [:ford :toyota :latacara]
+    (sr/select [:cars sr/MAP-KEYS] __))
+
+ ;; Try to just get the types of cars from latacara
+ (= [:prime :prime-zero]
+    (sr/select [:cars __ __] car-inventory))
+
+ ;; Let's try to get some Values instead of keys
+ ;; Let's start with selecting the vector of the two ford Focus cars we have at the dealership
+ (= [[{:doors 2 :color "red"} {:doors 2 :color "blue"}]]
+    (sr/select [:cars __ __] car-inventory))
+
+ ;; That was great, but what if we actually just want the maps instead of the vector
+ ;; (notice that the previous test is a vector inside of a vector)
+ (= [{:doors 2 :color "red"} {:doors 2 :color "blue"}]
+    (___ [:cars :ford __ sr/ALL] __))
+
+ ;; Let's get all of the cars from both ford types, the focus and the expedition
+ (= [{:doors 2 :color "red"} {:doors 2 :color "blue"} {:doors 4 :color "red"} {:doors 4 :color "black"}]
+    (sr/select [:cars :ford (sr/multi-path :focus :expedition) __] car-inventory))
+
+ ;; multi-path was cool, but imagine if you had 100 keys in the multi-path, that would be terrible
+ ;; let's see if we can get there with MAP-VALS
+ (= [{:doors 2 :color "red"} {:doors 2 :color "blue"} {:doors 4 :color "red"} {:doors 4 :color "black"}]
+    (sr/select [__ __ sr/MAP-VALS __] car-inventory))
+
+ ;; Great, so we can now traverse a map, going either by the absolute path or using some generalized special functions to get where we need to go
+ ;; So what is Eidolon?
+ ;; Eidolon is a latacora built specter library - Let's check it out 
+
+ ;; eidolon TREE-KEYS will provide all of the keys below whatever point in the map it is called
+ (= [:doors :color :doors :color :doors :color :doors :color :focus :expedition]
+    (sr/select [:cars :ford e/TREE-KEYS] __))
+
+ ;; what if instead of TREE-KEYS we wanted the TREE-LEAVES?
+ (= [2 "red" 2 "blue" 4 "red" 4 "black"]
+    (sr/select [:cars :ford ___] car-inventory))
+
+ )
+
+
+
+