bs.hs

{-# LANGUAGE BangPatterns #-}
module Main where
 
import qualified Data.ByteString as Byte
import qualified Data.ByteString.Char8 as B
import System.Environment (getArgs)
 
import Data.List (sortBy)
import qualified Data.HashMap.Strict as HM
import Data.Ord (comparing)

-- | equivalent to a-zA-Z ranges in D, doesn't handle unicode data (unlike Data.Char.isLetter)
rn c | (c >= 97) && (c <= 122) = c
     | (c >= 65) && (c <= 90) = c+32
     | otherwise = 32

createReport :: Int -> B.ByteString -> B.ByteString
createReport n =
    B.unlines 
    . map (\(w, count) -> B.append w $ B.pack (" " ++ show count)) 
    . take n 
    . sortBy (flip $ comparing snd)
    . HM.toList 
    . HM.fromListWith (\ !old !new -> old+new)
    . map (\w -> (w, 1))
    . B.words
    . Byte.map rn


main = getArgs >>= \[n] -> B.interact $ createReport (read n) 

test.hs

{-# LANGUAGE BangPatterns #-}
module Main where
 
import qualified Data.Text as T
import qualified Data.Text.IO as T

import System.Environment (getArgs)
import Data.List (sortBy)
import qualified Data.HashMap.Strict as HM
import Data.Ord (comparing)


createReport :: Int -> T.Text -> T.Text
createReport n =
    T.unlines 
    . map (\(w, count) -> T.append w $ T.pack ("  " ++ show count))
    . take n 
    . sortBy (flip $ comparing snd)
    . HM.toList 
    . HM.fromListWith (\ !old !new -> old+new)
    . map (\w -> (w, 1))
    . T.words
    . T.map rnl

main = getArgs >>= \[n] -> T.interact $ createReport (read n) 


-- | equivalent to a-zA-Z ranges in D, doesn't handle unicode data (unlike Data.Char.isLetter)
-- (I integrated the conversion to lower case since I was in ghci anyway)
rnl :: Char -> Char
rnl = \n -> case n of
  'a' -> 'a'
  'b' -> 'b'
  'c' -> 'c'
  'd' -> 'd'
  'e' -> 'e'
  'f' -> 'f'
  'g' -> 'g'
  'h' -> 'h'
  'i' -> 'i'
  'j' -> 'j'
  'k' -> 'k'
  'l' -> 'l'
  'm' -> 'm'
  'n' -> 'n'
  'o' -> 'o'
  'p' -> 'p'
  'q' -> 'q'
  'r' -> 'r'
  's' -> 's'
  't' -> 't'
  'u' -> 'u'
  'v' -> 'v'
  'w' -> 'w'
  'x' -> 'x'
  'y' -> 'y'
  'z' -> 'z'
  'A' -> 'a'
  'B' -> 'b'
  'C' -> 'c'
  'D' -> 'd'
  'E' -> 'e'
  'F' -> 'f'
  'G' -> 'g'
  'H' -> 'h'
  'I' -> 'i'
  'J' -> 'j'
  'K' -> 'k'
  'L' -> 'l'
  'M' -> 'm'
  'N' -> 'n'
  'O' -> 'o'
  'P' -> 'p'
  'Q' -> 'q'
  'R' -> 'r'
  'S' -> 's'
  'T' -> 't'
  'U' -> 'u'
  'V' -> 'v'
  'W' -> 'w'
  'X' -> 'x'
  'Y' -> 'y'
  'Z' -> 'z'
  _ -> '\n'