Contents

{-# LANGUAGE TypeFamilies #-}

module WordCount (wordCount) where

import Prelude hiding (null)
import Data.Char      (isAlphaNum)
import Data.Text      (Text, null, split, toLower)
import Data.MultiSet  (MultiSet, Occur, fromList, fromOccurList, toOccurList)

import qualified GHC.Exts (IsList(..))

wordCount :: Text -> Bag Text
wordCount = Bag
          . fromList
          . map toLower
          . wordsBy (not . isAlphaNum)

-- The `text` package misses this function that
-- exists in package `split`, but works on lists.
wordsBy :: (Char -> Bool) -> Text -> [Text]
wordsBy p = filter (not . null) . split p

-- MultiSet is not an instance of `IsList`, so we create
-- a newtype to wrap it, avoiding an orphan instance.
newtype Bag a = Bag { toMultiSet :: MultiSet a }

instance (Ord a) => GHC.Exts.IsList (Bag a)
  where
    type Item (Bag a) = (a, Occur)
    fromList = Bag . fromOccurList
    toList   = toOccurList . toMultiSet

Version data entries

5 entries across 5 versions & 1 rubygems

Version	Path
trackler-2.0.0.3	tracks/haskell/exercises/word-count/examples/success-newtype/src/WordCount.hs
trackler-2.0.0.2	tracks/haskell/exercises/word-count/examples/success-newtype/WordCount.hs
trackler-2.0.0.1	tracks/haskell/exercises/word-count/examples/success-newtype/WordCount.hs
trackler-2.0.0.0	tracks/haskell/exercises/word-count/examples/success-newtype/WordCount.hs
trackler-1.0.4.1	tracks/haskell/exercises/word-count/examples/success-newtype/WordCount.hs