Switch 'AT&T Park' to 'Oracle Park' on answer sheet

The word "do" seems to be missing in the final koan.

README.md

@@ -152,7 +152,7 @@ to add to existing koans.  So write some fun exercises, add your answers to
 
 Please follow the guidelines in
 http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html for
-commmit messages, and put your code in a feature branch (not master) before
+commit messages, and put your code in a feature branch (not master) before
 making the pull request. This makes patches easier to review.
 
 Feel free to contact me (Colin Jones / trptcolin) on Github or elsewhere if you

project.clj

@@ -1,4 +1,4 @@
-(defproject clojure-koans "0.5.1"
+(defproject clojure-koans "0.5.2-SNAPSHOT"
   :description "The Clojure koans."
   :dependencies [[org.clojure/clojure "1.10.0"]
                  [koan-engine "0.2.5"]]

resources/koans.clj

@@ -254,16 +254,35 @@
                    nil
                    \C
                    inc
-                   :park "AT&T Park"
+                   :park "Oracle Park"
                    'Giants
                    "Giants"]}]
 
  ["24_macros" {"__" [~(first form)
-                  ~(nth form 2)
-                  form
-                  (drop 2 form)
-                  "Hello, Macros!"
-                  10
-                  '(+ 9 1)]}]
+                     ~(nth form 2)
+                     form
+                     (drop 2 form)
+                     "Hello, Macros!"
+                     10
+                     '(+ 9 1)]}]
 
+ ["25_threading_macros" {"__" [{:a 1}
+                               "Hello world, and moon, and stars"
+                               "String with a trailing space"
+                               6
+                               1
+                               [2 3 4]
+                               12
+                               [1 2 3]]}]
+
+ ["26_transducers" {"__" ['(2 3 4)
+                          [2 4]
+                          [2 4]
+                          [2 4]
+                          6]}]
+
+ ["27_multimethods" {"__" ["Hello, World!"
+                           "Hello there"
+                           1
+                           6]}]
 ]

src/koans/02_strings.clj

@@ -39,7 +39,7 @@
   "Maybe you want to find the index of the first occurrence of a substring"
   (= 0 (string/index-of "hello world" __))
 
-  "Or maybe the last index of the same"
+  "Or maybe the last index of the same substring"
   (= __ (string/last-index-of "hello world, hello" "hello"))
 
   "But when something doesn't exist, nothing is found"

src/koans/05_sets.clj

@@ -12,7 +12,7 @@
   "Remember that a set is a *mathematical* set"
   (= __ (set '(1 1 2 2 3 3 4 4 5 5)))
 
-  "You can ask clojure for the union of two sets"
+  "You can ask Clojure for the union of two sets"
   (= __ (set/union #{1 2 3 4} #{2 3 5}))
 
   "And also the intersection"

src/koans/12_sequence_comprehensions.clj

@@ -20,7 +20,7 @@
      (for [x __ :when (odd? x)]
        x))
 
-  "Combinations of these transformations is trivial"
+  "Combinations of these transformations are trivial"
   (= '(1 9 25 49 81)
      (map (fn [x] (* x x))
           (filter odd? (range 10)))

src/koans/14_recursion.clj

@@ -35,10 +35,10 @@
   "Yet it becomes more difficult the more steps you take"
   (= '(6 5 4 3 2) (recursive-reverse [2 3 4 5 6]))
 
-  "Simple things may appear simple."
+  "Simple things may appear simple"
   (= 1 (factorial 1))
 
-  "They may require other simple steps."
+  "They may require other simple steps"
   (= 2 (factorial 2))
 
   "Sometimes a slightly bigger step is necessary"

src/koans/15_destructuring.clj

@@ -29,7 +29,7 @@
      (let [[first-name last-name :as full-name] ["Stephen" "Hawking"]]
        __))
 
-  "Break up maps by key"
+  "Break up maps by keys"
   (= "123 Test Lane, Testerville, TX"
      (let [{street-address :street-address, city :city, state :state} test-address]
        __))

src/koans/21_partition.clj

@@ -14,8 +14,8 @@
   "If you need to, you can start each sequence with an offset"
   (= '((0 1 2) (5 6 7) (10 11 12)) (partition 3 __ (range 13)))
 
-  "Consider padding the last sequence with some default values..."
+  "Consider padding the last sequence with some default values"
   (= '((0 1 2) (3 4 5) (6 :hello)) (partition 3 3 [__] (range 7)))
 
-  "... but notice that they will only pad up to the given sequence length"
+  "But notice that they will only pad up to the given sequence length"
   (= '((0 1 2) (3 4 5) __) (partition 3 3 [:these :are "my" "words"] (range 7))))

src/koans/22_group_by.clj

@@ -6,7 +6,7 @@
     [odds evens]))
 
 (meditations
-  "To categorize a collection by some function, use group-by."
+  "To categorize a collection by some function, use group-by"
   (= __ (group-by count ["hello" "world" "foo" "bar"]))
 
   "You can simulate filter + remove in one pass"

src/koans/23_meta.clj

@@ -40,7 +40,7 @@
          @(:world-series-titles (meta giants))))
 
   "You can also create a new object from another object with metadata"
-  (= {:league "National League" :park "AT&T Park"}
+  (= {:league "National League" :park "Oracle Park"}
      (meta (vary-meta giants
                       assoc __ __)))
 

src/koans/24_macros.clj

@@ -38,7 +38,7 @@
   "You can do better than that - hand crafting FTW!"
   (= '(* 10 2) (macroexpand '(infix-concise (10 * 2))))
 
-  "Things don't always work as you would like them to... "
+  "Things don't always work as you would like them to"
   (= '(+ 10 (2 * 3)) (macroexpand '(infix-concise (10 + (2 * 3)))))
 
   "Really, you don't understand recursion until you understand recursion"

src/koans/25_threading_macros.clj

@@ -0,0 +1,66 @@
+(ns koans.25-threading-macros
+  (:require [koan-engine.core :refer :all]))
+
+(def a-list
+  '(1 2 3 4 5))
+
+(def a-list-with-maps
+  '({:a 1} {:a 2} {:a 3}))
+
+(defn function-that-takes-a-map [map a b]
+  (get map :a))
+
+(defn function-that-takes-a-coll [a b coll]
+  (map :a coll))
+
+(meditations
+ "We can use thread first for more readable sequential operations"
+ (= __
+    (-> {}
+        (assoc :a 1)))
+
+ "Consider also the case of strings"
+ (= __
+    (-> "Hello world"
+        (str ", and moon")
+        (str ", and stars")))
+
+ "When a function has no arguments to partially apply, just reference it"
+ (= __
+    (-> "String with a trailing space "
+        clojure.string/trim))
+
+ "Most operations that take a scalar value as an argument can be threaded-first"
+ (= __
+    (-> {}
+        (assoc :a 1)
+        (assoc :b 2)
+        (assoc :c {:d 4
+                   :e 5})
+        (update-in [:c :e] inc)
+        (get-in [:c :e])))
+
+ "We can use functions we have written ourselves that follow this pattern"
+ (= __
+    (-> {}
+        (assoc :a 1)
+        (function-that-takes-a-map "hello" "there")))
+
+ "We can also thread last using ->>"
+ (= __
+    (->> [1 2 3]
+         (map inc)))
+
+ "Most operations that take a collection can be threaded-last"
+ (= __
+    (->> a-list
+         (map inc)
+         (filter even?)
+         (into [])
+         (reduce +)))
+
+ "We can use functions we have written ourselves that follow this pattern"
+ (= __
+    (->> a-list-with-maps
+         (function-that-takes-a-coll "hello" "there")
+         (into []))))

src/koans/26_transducers.clj

@@ -0,0 +1,30 @@
+(ns koans.26-transducers
+  (:require [koan-engine.core :refer :all]))
+
+(def example-transducer
+  (map inc))
+
+(def transforms
+  (comp (map inc)
+     (filter even?)))
+
+(meditations
+ "A sequence operation with only one argument often returns a transducer"
+ (= __
+    (sequence example-transducer [1 2 3]))
+
+ "Consider that sequence operations can be composed as transducers"
+ (= __
+    (transduce transforms conj [1 2 3]))
+
+ "We can do this eagerly"
+ (= __
+    (into [] transforms [1 2 3]))
+
+ "Or lazily"
+ (= __
+    (sequence transforms [1 2 3]))
+
+ "The transduce function can combine mapping and reduction"
+ (= __
+    (transduce transforms + [1 2 3])))

src/koans/27_multimethods.clj

@@ -0,0 +1,44 @@
+(ns koans.27-multimethods
+  (:require [koan-engine.core :refer :all]))
+
+(defmulti multimethod-without-args
+ (fn [keyword-arg] keyword-arg))
+
+(defmethod multimethod-without-args :first [_]
+ (str "Hello, World!"))
+
+(defmethod multimethod-without-args :second [_]
+ (str "Hello there"))
+
+(defmulti multimethod-with-args
+ (fn [opt-one opt-two] opt-one))
+
+(defmethod multimethod-with-args :path-one [_ opts]
+ (:first-opt opts))
+
+(defmethod multimethod-with-args :path-two [_ opts]
+ (let [numbers (:second-opt opts)]
+  (->> numbers
+       (map inc)
+       (reduce +))))
+
+(defmethod multimethod-with-args :path-three [_])
+
+(meditations
+ "A multimethod takes one or more arguments to dispatch on"
+ (= __
+    (multimethod-without-args :first))
+
+ "Though it can be ignored and represented by _ in defmethods"
+ (= __
+    (multimethod-without-args :second))
+
+ "Alternatively, we can use the arguments in defmethods"
+ (= __
+    (multimethod-with-args :path-one {:first-opt 1
+                                      :second-opt 2}))
+ 
+ "This allows us to do something different in each method implementation"
+ (= __
+    (multimethod-with-args :path-two {:first-opt 1
+                                      :second-opt [0 1 2]})))