Add proverb exercise (#142)

config.json

@@ -585,6 +585,17 @@
         ],
         "difficulty": 2
       },
+      {
+        "slug": "proverb",
+        "name": "Proverb",
+        "uuid": "fa8ffb0a-4936-4aad-8b8e-e77116aca614",
+        "practices": [],
+        "prerequisites": [
+          "strings",
+          "vectors"
+        ],
+        "difficulty": 3
+      },
       {
         "slug": "zipper",
         "name": "Zipper",

exercises/practice/proverb/.docs/instructions.md

@@ -0,0 +1,19 @@
+# Instructions
+
+For want of a horseshoe nail, a kingdom was lost, or so the saying goes.
+
+Given a list of inputs, generate the relevant proverb.
+For example, given the list `["nail", "shoe", "horse", "rider", "message", "battle", "kingdom"]`, you will output the full text of this proverbial rhyme:
+
+```text
+For want of a nail the shoe was lost.
+For want of a shoe the horse was lost.
+For want of a horse the rider was lost.
+For want of a rider the message was lost.
+For want of a message the battle was lost.
+For want of a battle the kingdom was lost.
+And all for the want of a nail.
+```
+
+Note that the list of inputs may vary; your solution should be able to handle lists of arbitrary length and content.
+No line of the output text should be a static, unchanging string; all should vary according to the input given.

exercises/practice/proverb/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "ErikSchierboom"
+  ],
+  "files": {
+    "solution": [
+      "src/proverb.cljs"
+    ],
+    "test": [
+      "test/proverb_test.cljs"
+    ],
+    "example": [
+      ".meta/src/example.cljs"
+    ]
+  },
+  "blurb": "For want of a horseshoe nail, a kingdom was lost, or so the saying goes. Output the full text of this proverbial rhyme.",
+  "source": "Wikipedia",
+  "source_url": "https://en.wikipedia.org/wiki/For_Want_of_a_Nail"
+}

exercises/practice/proverb/.meta/src/example.cljs

@@ -0,0 +1,16 @@
+(ns proverb
+  (:require [clojure.string :as str]))
+
+(defn last-line [subject] 
+  (str "And all for the want of a " subject "."))
+
+(defn- line [[cause-subject effect-subject]]
+  (str "For want of a " cause-subject " the " effect-subject " was lost."))
+
+(defn recite [subjects]
+  (if (empty? subjects) ""
+    (->> subjects
+    (partition 2 1)
+    (map line)
+    (#(conj (vec %) (last-line (first subjects))))
+    (str/join "\n"))))

exercises/practice/proverb/.meta/tests.toml

@@ -0,0 +1,21 @@
+# This is an auto-generated file. Regular comments will be removed when this
+# file is regenerated. Regenerating will not touch any manually added keys,
+# so comments can be added in a "comment" key.
+
+[e974b73e-7851-484f-8d6d-92e07fe742fc]
+description = "zero pieces"
+
+[2fcd5f5e-8b82-4e74-b51d-df28a5e0faa4]
+description = "one piece"
+
+[d9d0a8a1-d933-46e2-aa94-eecf679f4b0e]
+description = "two pieces"
+
+[c95ef757-5e94-4f0d-a6cb-d2083f5e5a83]
+description = "three pieces"
+
+[433fb91c-35a2-4d41-aeab-4de1e82b2126]
+description = "full proverb"
+
+[c1eefa5a-e8d9-41c7-91d4-99fab6d6b9f7]
+description = "four pieces modernized"

exercises/practice/proverb/deps.edn

@@ -0,0 +1,10 @@
+{:deps
+ {org.clojure/clojure {:mvn/version "1.10.1"}
+  org.clojure/clojurescript {:mvn/version "1.10.773"}}
+
+ :aliases
+ {:test
+  {:extra-paths ["test"]
+   :extra-deps
+   {olical/cljs-test-runner {:mvn/version "3.8.0"}}
+   :main-opts ["-m" "cljs-test-runner.main"]}}}

exercises/practice/proverb/src/proverb.cljs

@@ -0,0 +1,5 @@
+(ns proverb)
+
+(defn recite [] ;; <- arglist goes here
+    ;; your code goes here
+)

exercises/practice/proverb/test/proverb_test.cljs

@@ -0,0 +1,45 @@
+(ns proverb-test
+  (:require [clojure.test :refer [deftest is]]
+            [proverb :refer [recite]]
+            [clojure.string :as str]))
+
+(deftest zero-pieces
+  (is (=
+        (recite ())
+        "")))
+
+(deftest one-piece
+  (is (=
+        (recite '("nail"))
+        "And all for the want of a nail.")))
+
+(deftest two-pieces
+  (is (=
+        (recite '("nail" "shoe"))
+        (str/join "\n" ["For want of a nail the shoe was lost."
+                        "And all for the want of a nail."]))))
+
+(deftest three-pieces
+  (is (=
+        (recite '("nail" "shoe" "horse"))
+        (str/join "\n" ["For want of a nail the shoe was lost."
+                        "For want of a shoe the horse was lost."
+                        "And all for the want of a nail."]))))
+
+(deftest full-proverb
+  (is (= (recite '("nail" "shoe" "horse" "rider" "message" "battle" "kingdom"))
+         (str/join "\n" ["For want of a nail the shoe was lost."
+                         "For want of a shoe the horse was lost."
+                         "For want of a horse the rider was lost."
+                         "For want of a rider the message was lost."
+                         "For want of a message the battle was lost."
+                         "For want of a battle the kingdom was lost."
+                         "And all for the want of a nail."]))))
+
+(deftest four-pieces-modernized
+  (is (=
+        (recite '("pin" "gun" "soldier" "battle"))
+        (str/join "\n" ["For want of a pin the gun was lost."
+                        "For want of a gun the soldier was lost."
+                        "For want of a soldier the battle was lost."
+                        "And all for the want of a pin."]))))