Simple Haskell script for word counting
This is just a simple piece of code I put together to play with some Haskell when I realised I've not been writing nearly enough of the stuff.
It reads text from stdin and prints the words it finds together with how many times each one occurred.
It reads text from stdin and prints the words it finds together with how many times each one occurred.
1 2 module Main 3 where 4 5 import List 6 import Control.Arrow 7 8 type Comparator a = (a -> a -> Ordering) 9 10 ascending :: (Ord a) => (b -> a) -> Comparator b 11 ascending f x y = compare (f x) (f y) 12 13 descending :: (Ord a) => (b -> a) -> Comparator b 14 descending = flip . ascending 15 16 secondary :: Comparator a -> Comparator a -> Comparator a 17 secondary f g x y = case f x y of { 18 EQ -> g x y; 19 z -> z; } 20 21 -- Returns a list of unique elements together with their frequency. Listed in decreasing order of frequency, followed by 22 increasing order of the elements. 23 count :: (Ord a) => [a] -> [(a, Int)] 24 count = map (head &&& length) . sortBy (descending length `secondary` ascending head) . group . sort 25 26 main :: IO () 27 main = interact $ unlines . map (\(x, y) -> (take 20 $ x ++ repeat ' ') ++ " : " ++ show y) . count . words 28
