Add etl exercise (#123)

config.json

@@ -315,6 +315,18 @@
         "difficulty": 5,
         "topics": null
       },
+      {
+        "slug": "etl",
+        "name": "Etl",
+        "uuid": "c895c0f5-0fe5-4ce1-a3a9-b6cd911d9275",
+        "practices": [],
+        "prerequisites": [
+          "lists",          
+          "numbers",
+          "strings"
+        ],
+        "difficulty": 2
+      },
       {
         "slug": "difference-of-squares",
         "name": "Difference Of Squares",

exercises/practice/etl/.docs/instructions.md

@@ -0,0 +1,27 @@
+# Instructions
+
+Your task is to change the data format of letters and their point values in the game.
+
+Currently, letters are stored in groups based on their score, in a one-to-many mapping.
+
+- 1 point: "A", "E", "I", "O", "U", "L", "N", "R", "S", "T",
+- 2 points: "D", "G",
+- 3 points: "B", "C", "M", "P",
+- 4 points: "F", "H", "V", "W", "Y",
+- 5 points: "K",
+- 8 points: "J", "X",
+- 10 points: "Q", "Z",
+
+This needs to be changed to store each individual letter with its score in a one-to-one mapping.
+
+- "a" is worth 1 point.
+- "b" is worth 3 points.
+- "c" is worth 3 points.
+- "d" is worth 2 points.
+- etc.
+
+As part of this change, the team has also decided to change the letters to be lower-case rather than upper-case.
+
+~~~~exercism/note
+If you want to look at how the data was previously structured and how it needs to change, take a look at the examples in the test suite.
+~~~~

exercises/practice/etl/.docs/introduction.md

@@ -0,0 +1,16 @@
+# Introduction
+
+You work for a company that makes an online multiplayer game called Lexiconia.
+
+To play the game, each player is given 13 letters, which they must rearrange to create words.
+Different letters have different point values, since it's easier to create words with some letters than others.
+
+The game was originally launched in English, but it is very popular, and now the company wants to expand to other languages as well.
+
+Different languages need to support different point values for letters.
+The point values are determined by how often letters are used, compared to other letters in that language.
+
+For example, the letter 'C' is quite common in English, and is only worth 3 points.
+But in Norwegian it's a very rare letter, and is worth 10 points.
+
+To make it easier to add new languages, your team needs to change the way letters and their point values are stored in the game.

exercises/practice/etl/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "ErikSchierboom"
+  ],
+  "files": {
+    "solution": [
+      "src/etl.cljs"
+    ],
+    "test": [
+      "test/etl_test.cljs"
+    ],
+    "example": [
+      ".meta/src/example.cljs"
+    ]
+  },
+  "blurb": "Change the data format for scoring a game to more easily add other languages.",
+  "source": "Based on an exercise by the JumpstartLab team for students at The Turing School of Software and Design.",
+  "source_url": "https://turing.edu"
+}

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

@@ -0,0 +1,8 @@
+(ns etl
+  (:require [clojure.string :refer [lower-case]]))
+
+(defn transform [extract]
+  (into {}
+        (for [[score letters] extract
+              letter          letters]
+          [(lower-case letter) score])))

exercises/practice/etl/.meta/tests.toml

@@ -0,0 +1,15 @@
+# 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.
+
+[78a7a9f9-4490-4a47-8ee9-5a38bb47d28f]
+description = "single letter"
+
+[60dbd000-451d-44c7-bdbb-97c73ac1f497]
+description = "single score with multiple letters"
+
+[f5c5de0c-301f-4fdd-a0e5-df97d4214f54]
+description = "multiple scores with multiple letters"
+
+[5db8ea89-ecb4-4dcd-902f-2b418cc87b9d]
+description = "multiple scores with differing numbers of letters"

exercises/practice/etl/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/etl/src/etl.cljs

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

exercises/practice/etl/test/etl_test.cljs

@@ -0,0 +1,30 @@
+(ns etl-test
+  (:require [clojure.test :refer [deftest is]]
+            etl))
+
+(deftest transform-one-value
+  (is (= {"world" 1}
+         (etl/transform {1 ["WORLD"]}))))
+
+(deftest transform-more-values
+  (is (= {"world" 1 "gschoolers" 1}
+         (etl/transform {1 ["WORLD" "GSCHOOLERS"]}))))
+
+(deftest more-keys
+  (is (= {"apple" 1 "artichoke" 1 "boat" 2 "ballerina" 2}
+         (etl/transform {1 ["APPLE" "ARTICHOKE"], 2 ["BOAT" "BALLERINA"]}))))
+
+(deftest full-dataset
+  (is (= {"a"  1 "b"  3 "c" 3 "d" 2 "e" 1
+          "f"  4 "g"  2 "h" 4 "i" 1 "j" 8
+          "k"  5 "l"  1 "m" 3 "n" 1 "o" 1
+          "p"  3 "q" 10 "r" 1 "s" 1 "t" 1
+          "u"  1 "v"  4 "w" 4 "x" 8 "y" 4
+          "z" 10}
+         (etl/transform {1  (re-seq #"\w" "AEIOULNRST")
+                         2  (re-seq #"\w" "DG")
+                         3  (re-seq #"\w" "BCMP")
+                         4  (re-seq #"\w" "FHVWY")
+                         5  (re-seq #"\w" "K")
+                         8  (re-seq #"\w" "JX")
+                         10 (re-seq #"\w" "QZ")}))))