Add word-count exercise (closes #25)

config.json

@@ -10,6 +10,7 @@
      "pangram",
      "rna-transcription",
      "hamming",
+     "word-count",
      "bob"
   ],
   "deprecated": [

elm-package.json

@@ -10,6 +10,7 @@
         "./exercises/pangram",
         "./exercises/rna-transcription",
         "./exercises/hamming",
+        "./exercises/word-count",
         "./exercises/bob"
     ],
     "exposed-modules": [],

exercises/word-count/WordCount.elm

@@ -0,0 +1 @@
+module WordCount (..) where

exercises/word-count/WordCount.example

@@ -0,0 +1,24 @@
+module WordCount (..) where
+
+import String
+import Dict exposing (Dict)
+import Regex
+
+
+wordCount : String -> Dict String Int
+wordCount sentence =
+  sentence
+    |> String.toLower
+    |> depunctuate
+    |> String.words
+    |> List.foldl (\w d -> Dict.update w incrMaybe d) Dict.empty
+
+
+depunctuate : String -> String
+depunctuate =
+  Regex.replace Regex.All (Regex.regex "[^a-z0-9 ]") (\_ -> "")
+
+
+incrMaybe : Maybe Int -> Maybe Int
+incrMaybe maybe =
+  (Maybe.withDefault 0 maybe) + 1 |> Just

exercises/word-count/WordCountTests.elm

@@ -0,0 +1,55 @@
+module Main (..) where
+
+import Task
+import Console
+import ElmTest exposing (..)
+import Dict exposing (Dict)
+import WordCount exposing (wordCount)
+
+
+tests : Test
+tests =
+  suite
+    "Hamming"
+    [ test
+        "count one word"
+        (assertEqual
+          (Dict.fromList [ ( "word", 1 ) ])
+          (wordCount "word")
+        )
+    , test
+        "count one of each word"
+        (assertEqual
+          (Dict.fromList [ ( "one", 1 ), ( "of", 1 ), ( "each", 1 ) ])
+          (wordCount "one of each")
+        )
+    , test
+        "multiple occurrences of a word"
+        (assertEqual
+          (Dict.fromList [ ( "one", 1 ), ( "fish", 4 ), ( "two", 1 ), ( "red", 1 ), ( "blue", 1 ) ])
+          (wordCount "one fish two fish red fish blue fish")
+        )
+    , test
+        "ignore punctuation"
+        (assertEqual
+          (Dict.fromList [ ( "car", 1 ), ( "carpet", 1 ), ( "as", 1 ), ( "java", 1 ), ( "javascript", 1 ) ])
+          (wordCount "car : carpet as java : javascript!!&@$%^&")
+        )
+    , test
+        "include numbers"
+        (assertEqual
+          (Dict.fromList [ ( "testing", 2 ), ( "1", 1 ), ( "2", 1 ) ])
+          (wordCount "testing, 1, 2 testing")
+        )
+    , test
+        "normalize case"
+        (assertEqual
+          (Dict.fromList [ ( "go", 3 ), ( "stop", 2 ) ])
+          (wordCount "go Go GO Stop stop")
+        )
+    ]
+
+
+port runner : Signal (Task.Task x ())
+port runner =
+  Console.run (consoleRunner tests)

exercises/word-count/elm-package.json

@@ -0,0 +1,16 @@
+{
+    "version": "1.0.0",
+    "summary": "Exercism problems in Elm.",
+    "repository": "https://github.com/exercism/xelm.git",
+    "license": "BSD3",
+    "source-directories": [
+        "."
+    ],
+    "exposed-modules": [],
+    "dependencies": {
+        "deadfoxygrandpa/elm-test": "3.0.1 <= v < 4.0.0",
+        "elm-lang/core": "2.0.0 <= v < 4.0.0",
+        "laszlopandy/elm-console": "1.1.0 <= v < 2.0.0"
+    },
+    "elm-version": "0.15.0 <= v < 0.17.0"
+}